EX-1.1

ONEOK Partners, L.P., a Delaware limited partnership (the “Partnership”), proposes to issue and sell to the underwriters named in Schedule A annexed hereto (the “Underwriters”), for whom you are acting as representatives (the “Representatives”), an aggregate of 12,100,000 common units (the “Firm Units”), representing limited partner interests in the Partnership (the “Units”). In addition, the Partnership proposes to grant to the Underwriters the option to purchase from the Partnership up to an additional 1,815,000 Units (the “Additional Units”). The Firm Units and the Additional Units are hereinafter collectively sometimes referred to as the “Offered Units.” The Offered Units are described in the Prospectus which is referred to below. ONEOK Partners GP, L.L.C., a Delaware limited liability company, and the general partner of the Partnership, is referred to herein as the “General Partner.”

The Partnership has prepared and filed, in accordance with the provisions of the Securities Act of 1933, as amended, and the rules and regulations thereunder (collectively, the “Act”), with the Securities and Exchange Commission (the “Commission”) a registration statement on Form S-3ASR (File No. 333-183287) under the Act (the “registration statement”), including a prospectus, which registration statement incorporates by reference certain documents which the Partnership has filed, or will file, in accordance with the provisions of the Securities Exchange Act of 1934, as amended, and the rules and regulations thereunder (collectively, the “Exchange Act”). Such registration statement has become effective under the Act.

Except where the context otherwise requires, “Registration Statement,” as used herein, means the registration statement, as amended at the time of such registration statement’s effectiveness for purposes of Section 11 of the Act, as such section applies to the respective Underwriters (the “Effective Time”), including (i) all documents filed as a part thereof or incorporated or deemed to be incorporated by reference therein and (ii) any information contained or incorporated by reference in a prospectus filed with the Commission pursuant to Rule 424(b) under the Act, to the extent such information is deemed, pursuant to Rule 430B or Rule 430C under the Act, to be part of the registration statement at the Effective Time.

The Partnership has furnished to you, for use by the Underwriters and by dealers in connection with the offering of the Offered Units, copies of one or more preliminary prospectus supplements, and the documents incorporated by reference therein, relating to the Offered Units. Except where the context otherwise requires, “Pre-Pricing Prospectus,” as used herein, means each such preliminary prospectus supplement, in the form so furnished, including any basic prospectus (whether or not in preliminary form) furnished to you by the Partnership and attached to or used with such preliminary prospectus supplement. Except where the context otherwise requires, “Basic Prospectus,” as used herein, means any such basic prospectus and any basic prospectus furnished to you by the Partnership and attached to or used with the Prospectus Supplement (as defined below).

Except where the context otherwise requires, “Prospectus Supplement,” as used herein, means the final prospectus supplement, relating to the Offered Units, filed by the Partnership with the Commission pursuant to Rule 424(b) under the Act on or before the second business day after the date hereof (or such earlier time as may be required under the Act), in the form furnished by the Partnership to you for use by the Underwriters and by dealers in connection with the offering of the Offered Units.

Except where the context otherwise requires, “Prospectus,” as used herein, means the Prospectus Supplement together with the Basic Prospectus attached to or used with the Prospectus Supplement.

“Permitted Free Writing Prospectuses,” as used herein, means the documents listed on Schedule B attached hereto and each “road show” (as defined in Rule 433 under the Act), if any, related to the offering of the Offered Units contemplated hereby that is a “written communication” (as defined in Rule 405 under the Act). The Underwriters have not offered or sold and will not offer or sell, without the Company’s consent, any Offered Units by means of any “free writing prospectus” (as defined in Rule 405 under the Act) that is required to be filed by the Underwriters with the Commission pursuant to Rule 433 under the Act, other than a Permitted Free Writing Prospectus.

“Disclosure Package,” as used herein, means any Pre-Pricing Prospectus or Basic Prospectus, in either case together with any combination of one or more of the Permitted Free Writing Prospectuses, if any, and the information included in Schedule C hereto.

Any reference herein to the registration statement, the Registration Statement, any Basic Prospectus, any Pre-Pricing Prospectus, the Prospectus Supplement, the Prospectus or any Permitted Free Writing Prospectus shall be deemed to refer to and include the documents, if any, incorporated by reference, or deemed to be incorporated by reference, therein (the “Incorporated Documents”), including, unless the context otherwise requires, the documents, if any, filed as exhibits to such Incorporated Documents. Any reference herein to the terms “amend,” “amendment” or “supplement” with respect to the Registration Statement, any Basic Prospectus, any Pre-Pricing Prospectus, the Prospectus Supplement, the Prospectus or any Permitted Free Writing Prospectus shall be deemed to refer to and include the filing of any document under the Exchange Act on or after the initial effective date of the Registration Statement, or the date of such Basic Prospectus, such Pre-Pricing Prospectus, the Prospectus Supplement, the Prospectus

or such Permitted Free Writing Prospectus, as the case may be, and deemed to be incorporated therein by reference.

As used in this Agreement, “business day” shall mean a day on which the New York Stock Exchange (the “NYSE”) is open for trading. The terms “herein,” “hereof,” “hereto,” “hereinafter” and similar terms, as used in this Agreement, shall in each case refer to this Agreement as a whole and not to any particular section, paragraph, sentence or other subdivision of this Agreement. The term “or,” as used herein, is not exclusive.

Concurrent with the issue and sale of the Offered Units by the Partnership pursuant to the terms of this Agreement, the General Partner will make a capital contribution to the Partnership in exchange for additional general partner interests in accordance with the requirements of the Partnership Agreement (the “GP Contribution”).

1. Sale and Purchase. Upon the basis of the representations and warranties and subject to the terms and conditions herein set forth, the Partnership agrees to issue and sell to the respective Underwriters and each of the Underwriters, severally and not jointly, agrees to purchase from the Partnership the number of Firm Units set forth opposite the name of such Underwriter in Schedule A attached hereto, subject to adjustment in accordance with Section 8 hereof, in each case at a purchase price of $51.35 per Unit. The Partnership is advised by you that the Underwriters intend (i) to make a public offering of their respective portions of the Firm Units as soon after the effectiveness of this Agreement as in your judgment is advisable and (ii) initially to offer the Firm Units upon the terms set forth in the Prospectus. You may from time to time increase or decrease the public offering price after the initial public offering to such extent as you may determine.

In addition, the Partnership hereby grants to the several Underwriters the option (the “Option”) to purchase, and upon the basis of the representations and warranties and subject to the terms and conditions herein set forth, the Underwriters shall have the right to purchase, severally and not jointly, from the Partnership, ratably in accordance with the number of Firm Units to be purchased by each of them, all or a portion of the Additional Units at the same purchase price per unit to be paid by the Underwriters to the Partnership for the Firm Units. The Option may be exercised by the Representatives on behalf of the several Underwriters at any time and from time to time on or before the thirtieth day following the date of the Prospectus Supplement, by written notice to the Partnership. Such notice shall set forth the aggregate number of Additional Units as to which the Option is being exercised and the date and time when the Additional Units are to be delivered (any such date and time being herein referred to as an “additional time of purchase”); provided, however, that no additional time of purchase shall be earlier than the “time of purchase” (as defined below) nor earlier than the second business day after the date on which the Option shall have been exercised nor later than the tenth business day after the date on which the Option shall have been exercised. The number of Additional Units to be sold to each Underwriter shall be the number which bears the same proportion to the aggregate number of Additional Units being purchased as the number of Firm Units set forth opposite the name of such Underwriter on Schedule A hereto bears to the total number of Firm

Units (subject, in each case, to such adjustment as the Representatives may determine to eliminate fractional common units), subject to adjustment in accordance with Section 8 hereof.

2. Payment and Delivery. Payment of the purchase price for the Firm Units shall be made to the Partnership by Federal Funds wire transfer against delivery of the certificates for the Firm Units to you through the facilities of The Depository Trust Company (“DTC”) for the respective accounts of the Underwriters. Such payment and delivery shall be made at 9:00 A.M., New York City time, on May 16, 2014 (unless another time shall be agreed to by you and the Partnership or unless postponed in accordance with the provisions of Section 8 hereof). The time at which such payment and delivery are to be made is hereinafter sometimes called the “time of purchase.” Electronic transfer of the Firm Units shall be made to you at the time of purchase in such names and in such denominations as you shall specify.

Payment of the purchase price for the Additional Units shall be made at the applicable additional time of purchase in the same manner and at the same office as the payment for the Firm Units. Electronic transfer of the Additional Units shall be made to you at the applicable additional time of purchase in such names and in such denominations as you shall specify.

Deliveries of the documents described in Section 6 hereof with respect to the purchase of the Offered Units shall be made at the offices of Shearman & Sterling LLP at 599 Lexington Avenue, New York, New York, at 9:00 A.M., New York City time, on the date of the closing of the purchase of the Firm Units or the Additional Units, as the case may be.

3. Representations and Warranties of the Partnership. The Partnership represents and warrants to and agrees with each of the Underwriters that:

(a) The Registration Statement has heretofore become effective under the Act; no stop order of the Commission preventing or suspending the use of any Basic Prospectus, any Pre-Pricing Prospectus, the Prospectus Supplement, the Prospectus or any Permitted Free Writing Prospectus, or the effectiveness of the Registration Statement, has been issued, and no proceedings for such purpose have been instituted or, to the Partnership’s knowledge, are contemplated by the Commission;

(b) The Registration Statement, at the date hereof, meets the requirements set forth in Rule 415(a)(1)(x). The initial Effective Time of the Registration Statement was not earlier than the date three years before the date hereof.

(c) the Registration Statement complied when it became effective, complies as of the date hereof and, as amended or supplemented, at the time of purchase, each additional time of purchase, if any, and at all times during which a prospectus is required by the Act to be delivered (whether physically or through compliance with Rule 172 under the Act or any similar rule) in connection with any sale of Offered Units, will comply, in all material respects, with the requirements of the Act; the conditions to the use of Form S-3 in connection with the offering and sale of the Offered Units as contemplated hereby have been satisfied; the Registration Statement constitutes an “automatic shelf registration statement” (as defined in Rule 405 under the Act); the

Partnership has not received, from the Commission, a notice, pursuant to Rule 401(g)(2), of objection to the use of the automatic shelf registration statement form; as of the determination date applicable to the Registration Statement (and any amendment thereof) and the offering contemplated hereby, the Partnership is a “well-known seasoned issuer” as defined in Rule 405 under the Act; the Registration Statement meets, and the offering and sale of the Offered Units as contemplated hereby complies with, the requirements of Rule 415 under the Act (including, without limitation, Rule 415(a)(5) under the Act); the Registration Statement did not, as of the Effective Time, contain an untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading; each Pre-Pricing Prospectus complied, at the time it was filed with the Commission, and complies as of the date hereof, in all material respects with the requirements of the Act; at no time during the period that begins on the earlier of the date of such Pre-Pricing Prospectus and the date such Pre-Pricing Prospectus was filed with the Commission and ends at the time of purchase did or will any Pre-Pricing Prospectus, as then amended or supplemented, include an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading, and at no time during such period did or will any Pre-Pricing Prospectus, as then amended or supplemented, together with any combination of one or more of the then issued Permitted Free Writing Prospectuses, if any, include an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading; each Basic Prospectus complied or will comply, as of its date and the date it was or will be filed with the Commission, complies as of the date hereof (if filed with the Commission on or prior to the date hereof) and, at the time of purchase, each additional time of purchase, if any, and at all times during which a prospectus is required by the Act to be delivered (whether physically or through compliance with Rule 172 under the Act or any similar rule) in connection with any sale of Offered Units, will comply, in all material respects, with the requirements of the Act; each of the Prospectus Supplement and the Prospectus will comply, as of the date that it is filed with the Commission, the date of the Prospectus Supplement, the time of purchase, each additional time of purchase, if any, and at all times during which a prospectus is required by the Act to be delivered (whether physically or through compliance with Rule 172 under the Act or any similar rule) in connection with any sale of Offered Units, in all material respects, with the requirements of the Act (in the case of the Prospectus, including, without limitation, Section 10(a) of the Act); at no time during the period that begins on the earlier of the date of the Prospectus Supplement and the date the Prospectus Supplement is filed with the Commission and ends at the later of the time of purchase, the latest additional time of purchase, if any, and the end of the period during which a prospectus is required by the Act to be delivered (whether physically or through compliance with Rule 172 under the Act or any similar rule) in connection with any sale of Offered Units did or will any Prospectus Supplement or the Prospectus, as then amended or supplemented, include an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading; at no time during the period that begins on the date of such Permitted Free Writing Prospectus and ends at the time of purchase did or will any

Permitted Free Writing Prospectus include an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading; provided, however, that the Partnership makes no representation or warranty in this Section 3(c) with respect to any statement contained in the Registration Statement, any Pre-Pricing Prospectus, the Prospectus or any Permitted Free Writing Prospectus in reliance upon and in conformity with information concerning an Underwriter and furnished in writing by or on behalf of such Underwriter through you to the Partnership expressly for use in the Registration Statement, such Pre-Pricing Prospectus, the Prospectus or such Permitted Free Writing Prospectus; each Incorporated Document, at the time such document was filed with the Commission or at the time such document became effective, as applicable, complied, in all material respects, with the requirements of the Exchange Act and did not include an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading;

(d) prior to the execution of this Agreement, the Partnership has not, directly or indirectly, offered or sold any Offered Units by means of any “prospectus” (within the meaning of the Act) or used any “prospectus” (within the meaning of the Act) in connection with the offer or sale of the Offered Units, in each case other than the Pre-Pricing Prospectuses and the Permitted Free Writing Prospectuses, if any; the Partnership has not, directly or indirectly, prepared, used or referred to any Permitted Free Writing Prospectus except in compliance with Rule 163 or with Rules 164 and 433 under the Act; assuming that such Permitted Free Writing Prospectus is so sent or given after the Registration Statement was filed with the Commission (and after such Permitted Free Writing Prospectus was, if required pursuant to Rule 433(d) under the Act, filed with the Commission), the sending or giving, by any Underwriter, of any Permitted Free Writing Prospectus will satisfy the provisions of Rule 164 and Rule 433 (without reliance on subsections (b), (c) and (d) of Rule 164); the conditions set forth in one or more of subclauses (i) through (iv), inclusive, of Rule 433(b)(1) under the Act are satisfied, and the registration statement relating to the offering of the Offered Units contemplated hereby, as initially filed with the Commission, includes a prospectus that, other than by reason of Rule 433 or Rule 431 under the Act, satisfies the requirements of Section 10 of the Act; neither the Partnership nor the Underwriters are disqualified, by reason of subsection (f) or (g) of Rule 164 under the Act, from using, in connection with the offer and sale of the Offered Units, “free writing prospectuses” (as defined in Rule 405 under the Act) pursuant to Rules 164 and 433 under the Act; the Partnership is not an “ineligible issuer” (as defined in Rule 405 under the Act) as of the eligibility determination date for purposes of Rules 164 and 433 under the Act with respect to the offering of the Offered Units contemplated by the Registration Statement; the parties hereto agree and understand that the content of any and all “road shows” (as defined in Rule 433 under the Act) related to the offering of the Offered Units contemplated hereby is solely the property of the Partnership;

(e) as of the date of this Agreement, the Partnership has an authorized and outstanding capitalization as set forth in the sections of the Registration Statement, the Pre-Pricing Prospectuses and the Prospectus entitled “Capitalization” and “Description of

Common Units Representing Limited Partner Interests” (and any similar sections or information, if any, contained in any Permitted Free Writing Prospectus), and, as of the time of purchase and any additional time of purchase, as the case may be, the Partnership shall have an authorized and outstanding capitalization as set forth in the sections of the Registration Statement, the Pre-Pricing Prospectuses and the Prospectus entitled “Capitalization” and “Description of Common Units Representing Limited Partner Interests” (and any similar sections or information, if any, contained in any Permitted Free Writing Prospectus), except for such adjustments as are necessary to reflect the offer and sale of the Offered Units;

(f) as of April 29, 2014, the limited partners of the Partnership held limited partner interests in the Partnership aggregating a 98.0% Partnership Interest (as defined in the Third Amended and Restated Agreement of Limited Partnership of the Partnership, as amended (the “Partnership Agreement”)) (subject to the provisions of the Partnership Agreement), such limited partner interests being represented by a total of 160,076,263 outstanding Units and 72,988,252 outstanding Class B Units (collectively, the “Limited Partner Units”); as of the time of purchase and each additional time of purchase, if any, the Limited Partner Units and the limited partner interests represented thereby were authorized by the Partnership Agreement and are validly issued, fully paid (to the extent required under the Partnership Agreement) and non-assessable (except as described in the Partnership Agreement and except as set forth in Sections 17-303, 17-607 and 17-804 of the Delaware Revised Uniform Limited Partnership Act (the “DRULPA”));

(g) the Partnership has been duly formed and is validly existing under the DRULPA and each of its “significant subsidiaries” (as defined in Rule 1-02 of Regulation S-X) (collectively, the “Subsidiaries” and each a Subsidiary) has been duly formed, is validly existing as a corporation, limited liability company or limited partnership, as the case may be, and is in good standing under the laws of the jurisdiction in which it is formed. The Partnership has all the requisite limited partnership power and authority and each of its Subsidiaries has full corporate, limited liability company or partnership power, as the case may be, and authority to own or lease, as the case may be, and to operate its properties and conduct its business in all material respects as described in the Disclosure Package and the Prospectus, and is duly qualified or registered to do business as a foreign entity and is in good standing under the laws of each jurisdiction which requires such qualification or registration, except where the failure to be so qualified or registered or in good standing would not reasonably be expected to (i) have a material adverse effect on the condition (financial or otherwise), earnings, cash flow, business affairs or business prospects of the Partnership and its subsidiaries, considered as one enterprise (a “Material Adverse Effect”), or (ii) subject the limited partners of the Partnership to any material liability or disability;

(h) all the outstanding equity interests of each Subsidiary have been duly and validly authorized and issued in accordance with such Subsidiary’s governing documents and are fully paid (in the case of any Subsidiary that is a limited liability company, to the extent required by such Subsidiary’s limited liability company agreement, and in the case of any Subsidiary that is a limited partnership, to the extent required by such Subsidiary’s agreement of limited partnership) and nonassessable (in the case of any Subsidiary that is

a limited liability company, except as such nonassessability may be affected by Sections 18-607 and 18-804 of the Delaware Revised Limited Liability Company Act or by Sections 2030, 2031 and 2040 of the Oklahoma Limited Liability Company Act, and in the case of any Subsidiary that is a limited partnership, except as such nonassessability may be affected by Sections 17-303, 17-607 and 17-804 of the DRULPA and matters included in such Subsidiary’s agreement of limited partnership), and all outstanding equity interests of the Subsidiaries are owned by the Partnership either directly or through wholly owned subsidiaries free and clear of any perfected security interest or any other security interests, claims or liens (“Liens”), except for any such Liens on the outstanding equity interests of the Subsidiaries that are described in the Disclosure Package and the Prospectus;

(i) the Offered Units have been duly and validly authorized and, when issued and delivered against payment therefor as provided herein, will be duly and validly issued, fully paid (to the extent required under the Partnership Agreement) and non-assessable (except as described in the Partnership Agreement and except as set forth in Sections 17-303, 17-607 and 17-804 of the DRULPA) and free of statutory and contractual preemptive rights, resale rights, rights of first refusal and similar rights; the Offered Units, when issued and delivered against payment therefor as provided herein, will be free of any restriction upon the voting or transfer thereof pursuant to the Partnership’s Partnership Agreement or any agreement or other instrument to which the Partnership is a party; and the statements under the caption “Description of common units representing limited partner interests” in the Basic Prospectus and contained or incorporated by reference in the Registration Statement, insofar as such statements summarize certain provision of documents referred to therein, fairly summarize such provisions in all material respects;

(j) the Units, including the Offered Units, conform in all material respects to the description thereof, if any, contained or incorporated by reference in the Registration Statement, the Pre-Pricing Prospectuses, the Prospectus and the Permitted Free Writing Prospectuses, if any; and the certificates for the Offered Units are in due and proper form;

(k) this Agreement has been duly authorized, executed and delivered by or on behalf of the Partnership;

(l) neither the Partnership nor any Subsidiary is in violation or default of (i) any provisions of the Partnership Agreement or other governing documents of the Partnership or the governing documents of such Subsidiary, as the case may be, (ii) the terms of any indenture, contract, lease, mortgage, deed of trust, note agreement, loan agreement or other agreement, obligation, condition, covenant or instrument to which it is a party or bound or to which its property is subject, or (iii) any statute, law, rule, regulation, judgment, order or decree of any court, regulatory body, administrative agency, governmental body, arbitrator or other authority having jurisdiction over the Partnership or such Subsidiary or any of its properties, as applicable, except in the case of clauses (ii) and (iii) as would not reasonably be expected to have a Material Adverse Effect or as could not materially impair the ability of the Partnership to perform its obligations under this Agreement;

(m) neither the issuance and sale of the Offered Units nor the consummation of any other of the transactions herein contemplated nor the fulfillment of the terms hereof will conflict with, result in a breach or violation of, or imposition of any lien, charge or encumbrance upon any property or assets of the Partnership or any of its Subsidiaries pursuant to (i) the provisions of the Partnership Agreement or other governing documents of the Partnership or any of the governing documents of any of its Subsidiaries, (ii) the terms of any indenture, contract, lease, mortgage, deed of trust, note agreement, loan agreement or other agreement, obligation, condition, covenant or instrument to which the Partnership or any of its Subsidiaries is a party or bound or to which its or their property is subject, or (iii) any statute, law, rule, regulation, judgment, order or decree applicable to the Partnership or any of its Subsidiaries of any court, regulatory body, administrative agency, governmental body, arbitrator or other authority having jurisdiction over the Partnership or any of its Subsidiaries or any of its or their properties, which conflicts, breaches, violations or defaults, in the case of clauses (ii) or (iii), would reasonably be expected, individually or in the aggregate, to have a Material Adverse Effect;

(n) no consent, approval, authorization, filing with or order of any court or governmental agency or body is required in connection with the transactions contemplated herein except (i) such as have been obtained under the Act, and (ii) such as may be required under the blue sky laws of any jurisdiction or the by-laws and rules of the Financial Industry Regulatory Authority (“FINRA”) in connection with the purchase and distribution by the Underwriters of the Offered Units in the manner contemplated herein and in the Disclosure Package and the Prospectus or (iii) such that the failure to obtain would not reasonably be expected to result in a Material Adverse Effect;

(o) except for the obligation of the General Partner under the Partnership Agreement to make such investments as are required in order to maintain a 2.0% interest in the Partnership, such rights as have been duly waived and as described in the Registration Statement (excluding the exhibits thereto), each Pre-Pricing Prospectus and the Prospectus, (i) no person has the right, contractual or otherwise, to cause the Partnership to issue or sell to it Units or other equity interests of the Partnership, (ii) no person has any preemptive rights, resale rights, rights of first refusal or other rights to purchase Units or other equity interests in the Partnership and (iii) no person has the right to act as an underwriter or as a financial advisor to the Partnership in connection with the offer and sale of the Offered Units; except for such rights as have been duly waived, no person has the right, contractual or otherwise, to cause the Partnership to register under the Act any Units or other equity interests in the Partnership, or to include any such Units or other interests in the Registration Statement or the offering contemplated thereby;

(p) the Partnership and its Subsidiaries possess all licenses, certificates, permits and other authorizations issued by the appropriate federal, state or foreign regulatory authorities necessary to conduct their respective businesses, except for such licenses, certificates, permits and other authorizations that, if not obtained, would not reasonably be expected to have, individually or in the aggregate, a Material Adverse Effect, and neither the Partnership nor any such Subsidiary has received any notice of proceedings relating to the revocation or modification of any such certificate, authorization or permit which, individually or in the aggregate, if the subject of an

unfavorable decision, ruling or finding, would reasonably be expected to have a Material Adverse Effect, except as set forth in or contemplated in the Disclosure Package and the Prospectus;

(q) other than as set forth in the Pre-Pricing Prospectus, the Prospectus and the Registration Statement, no action, suit or proceeding by or before any court or governmental agency, authority or body or any arbitrator involving the Partnership or any of its Subsidiaries or its or their property is pending or, to the Partnership’s knowledge, threatened that (i) would reasonably be expected to have a material adverse effect on the performance of this Agreement or the consummation of any of the transactions contemplated hereby or (ii) would reasonably be expected to have a Material Adverse Effect;

(r) PricewaterhouseCoopers LLP, who has performed certain procedures with respect to certain financial statements of the Partnership and its consolidated subsidiaries included, or incorporated by reference, in the Registration Statement, the Pre-Pricing Prospectuses and the Prospectus, is an independent registered public accounting firm with respect to the Partnership as required by the Act and the Public Company Accounting Oversight Board (United States) and its applicable published rules and regulations;

(s) the historical consolidated financial statements of the Partnership and its consolidated subsidiaries included or incorporated by reference in the Pre-Pricing Prospectus, the Prospectus and the Registration Statement present fairly in all material respects the consolidated financial condition, results of operations and cash flows of the Partnership as of the dates and for the periods indicated, comply as to form in all material respects with the applicable accounting requirements of the Act and have been prepared in conformity with generally accepted accounting principles applied on a consistent basis throughout the periods involved (except as otherwise noted therein);

(t) the interactive data in eXtensible Business Reporting Language (“XBRL”) included or incorporated by reference in the Registration Statement, the Prospectus and the Disclosure Package fairly presents the information called for in all material respects and has been prepared in accordance with the Commission’s rules and guidelines applicable thereto;

(u) the Partnership has obtained for the benefit of the Underwriters the agreement (a “Lock-Up Agreement”), in the form set forth as Exhibit A hereto, of each party named in Exhibit A-1 hereto;

(v) the Partnership is not and, after giving effect to the offering and sale of the Offered Units and the application of the proceeds thereof as described in the Disclosure Package and the Prospectus, will not be an “investment company” as defined in the Investment Company Act of 1940, as amended (the “Investment Company Act”);

(w) each of the Partnership and each of its Subsidiaries owns or leases all such properties as are necessary to the conduct of its operations as presently conducted except where the failure to do so does not materially interfere with the ownership, operation or

benefits of operation of such businesses or materially increase the cost of operation or ownership of such businesses, provided that (a) with respect to the transmission and gathering pipelines of the Partnership and the Subsidiaries that own such pipelines and right-of-way interests related thereto (the “Pipeline Properties”), the foregoing shall only constitute a representation that such Subsidiaries have sufficient title to enable them to use such Pipeline Properties in their businesses as they have been used in the past and as are proposed to be used in the future and will not materially increase the cost of such use, and (b) with respect to any real property, buildings and equipment held under lease by the Subsidiaries, such real property, buildings and equipment are held by the Subsidiaries under valid, subsisting and enforceable leases with such exceptions as are not material and do not interfere with the use made and proposed to be made of such real property, buildings and equipment for such Subsidiary;

(x) the Partnership and its Subsidiaries own, possess, license or have other rights to use, on reasonable terms, all material patents, patent applications, trade and service marks, trade and service mark registrations, trade names, copyrights, licenses, inventions, trade secrets, technology, know-how and other intellectual property (collectively, the “Intellectual Property”) necessary for the conduct of the Partnership’s business as now conducted or as proposed in the Prospectus to be conducted, except for failures of ownership or use that would not reasonably be expected to have a Material Adverse Effect. Additionally, (a) to the Partnership’s knowledge, there are no rights of third parties to any such Intellectual Property; (b) to the Partnership’s knowledge, there is no infringement by third parties of any such Intellectual Property; (c) there is no pending or, to the Partnership’s knowledge, threatened action, suit, proceeding or claim by others challenging the Partnership’s rights in or to any such Intellectual Property; and (d) to the Partnership’s knowledge, there is no pending or threatened action, suit, proceeding or claim by others that the Partnership infringes or otherwise violates any patent, trademark, copyright, trade secret or other proprietary rights of others, in the case of each of clauses (a), (b), (c) and (d) which would be reasonably expected to have a Material Adverse Effect;

(y) no labor problem or dispute with the employees of the Partnership or any of its Subsidiaries exists or, to the Partnership’s knowledge, is threatened or imminent, that would reasonably be expected to have a Material Adverse Effect;

(aa) the Partnership and its Subsidiaries (i) are in compliance with any and all applicable federal, state and local laws and regulations relating to the protection of human health and safety, the environment or hazardous or toxic substances or wastes, pollutants or contaminants (“Environmental Laws”), (ii) have received and are in compliance with all permits, licenses or other approvals required of them under applicable Environmental Laws to conduct their respective businesses and (iii) have not received notice of any actual or potential liability under any Environmental Law, except where such non-compliance with Environmental Laws, failure to receive or comply with required permits, licenses or other approvals, or liability would not, individually or in the aggregate, reasonably be expected to have a Material Adverse Effect, and except as set forth in or

contemplated in the Disclosure Package and the Prospectus. Neither the Partnership nor any of the Subsidiaries has been named as a “potentially responsible party” under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980, as amended, except (y) with respect to any matters that, individually or in the aggregate, would not reasonably be expected to have a Material Adverse Effect or (z) as set forth in or contemplated in the Disclosure Package and the Prospectus;

(bb) in the ordinary course of its business, the Partnership periodically reviews the effect of Environmental Laws on the business, operations and properties of the Partnership and the Subsidiaries, in the course of which it identifies and evaluates associated costs and liabilities (including, without limitation, any capital or operating expenditures required for clean-up, closure of properties or compliance with Environmental Laws, or any permit, license or approval, any related constraints on operating activities and any potential liabilities to third parties). On the basis of such review, the Partnership has reasonably concluded that such associated costs and liabilities would not, individually or in the aggregate, reasonably be expected to have a Material Adverse Effect;

(cc) the Partnership has filed all foreign, federal, state and local tax returns that are required to be filed or has requested extensions thereof and has paid all taxes required to be paid by it and any other assessment, fine or penalty levied against it, to the extent that any of the foregoing is due and payable, except for (i) those failures to file or pay that would not reasonably be expected to have a Material Adverse Effect, (ii) any such tax payment, assessment, fine or penalty that is currently being contested in good faith, or (iii) those failures to file or pay set forth in or contemplated in the Disclosure Package and the Prospectus;

(dd) there are no transfer taxes or other similar fees or charges under Federal law or the laws of any state, or any political subdivision thereof, required to be paid by the Partnership in connection with the execution and delivery of this Agreement or the issuance and sale by the Partnership of the Offered Units;

(ee) the Partnership and the Subsidiaries are insured by insurers that the Partnership has no reason to believe are not of recognized financial responsibility against such losses and risks and in such amounts as the Partnership believes are prudent and customary in the businesses in which they are engaged;

(ff) the Partnership and each of its subsidiaries maintain a system of internal accounting controls sufficient to provide reasonable assurance that (i) transactions are executed in accordance with management’s general or specific authorizations; (ii) transactions are recorded as necessary to permit preparation of financial statements in conformity with generally accepted accounting principles and to maintain asset accountability; (iii) access to assets is permitted only in accordance with management’s general or specific authorization; (iv) the recorded accountability for assets is compared with the existing assets at reasonable intervals and appropriate action is taken with respect to any differences; and (v) the interactive data in XBRL included or incorporated by reference in the Registration Statement, the Prospectus and the Disclosure Package

has been prepared in accordance with the Commission’s applicable rules and guidelines. Since the date of the most recent audited balance sheet of the Partnership and its consolidated subsidiaries audited by PricewaterhouseCoopers LLP and reviewed by the board of directors of the General Partner of the Partnership, (i) the Partnership has not been advised of (A) any significant deficiencies in the design or operations of internal control over financial reporting that could adversely affect the ability of the Partnership and each of its subsidiaries to record, process, summarize and report financial data, or any material weaknesses in internal control over financial reporting and (B) any fraud, whether or not material, that involves management or other employees who have a significant role in the internal control over financial reporting of the Partnership and each of its subsidiaries, and (ii) there have been no changes in internal control over financial reporting, including any corrective actions with regard to significant deficiencies and material weaknesses, that has materially affected, or is reasonably likely to materially affect, the Partnership’s internal control over financial reporting;

(gg) the Partnership and its subsidiaries maintain “disclosure controls and procedures” (as such term is defined in Rule 13a-15(e) under the Exchange Act);

(hh) the Partnership is in compliance in all material respects with the applicable provisions of the Sarbanes-Oxley Act of 2002 and the rules and regulations promulgated in connection therewith, including Section 402 thereof related to loans to officers and directors and Sections 302 and 906 related to certifications;

(ii) neither the Partnership nor any of its Subsidiaries nor, to the Partnership’s knowledge, any director, officer, agent, or employee of the Partnership or any of its Subsidiaries is aware of or has taken any action, directly or indirectly, that would result in a violation by such persons of the Foreign Corrupt Practices Act of 1977, as amended, and the rules and regulations thereunder, and the Partnership and its Subsidiaries have instituted and maintain policies and procedures designed to ensure, and which are reasonably expected to continue to ensure, continued compliance therewith;

(jj) the operations of the Partnership and its Subsidiaries are and have been conducted in compliance in all material respects with applicable financial recordkeeping and reporting requirements of the Currency and Foreign Transactions Reporting Act of 1970, as amended, and the money laundering statutes of all applicable jurisdictions (collectively, the “Money Laundering Laws”) and no action, suit or proceeding by or before any court or governmental agency, authority or body or any arbitrator involving the Partnership or any of its Subsidiaries with respect to the Money Laundering Laws is pending or, to the Partnership’s knowledge, threatened;

(kk) neither the Partnership nor any of its Subsidiaries nor, to the Partnership’s knowledge, any director, officer, agent, or employee of the Partnership or any of its Subsidiaries is currently subject to any U.S. sanctions administered by the Office of Foreign Assets Control of the U.S. Treasury Department (“OFAC”); and the Partnership will not directly or indirectly use the proceeds of the offering, or lend, contribute or otherwise make available such proceeds to any Subsidiary, joint venture partner or other

person or entity, for the purpose of financing the activities of any person currently subject to any U.S. sanctions administered by OFAC;

(ll) the Partnership has not received any notice from the NYSE regarding the delisting of the Units from the NYSE;

(mm) neither the Partnership nor any of the Subsidiaries have taken, directly or indirectly, any action designed to or that would constitute or that might reasonably be expected to cause or result in, under the Exchange Act or otherwise, stabilization or manipulation of the price of any security of the Partnership to facilitate the sale or resale of the Offered Units;

(nn) there is no contract or other document of a character required to be described in the Registration Statement or Basic Prospectus, or to be filed as an exhibit to the Registration Statement, which is not described or filed as required (and the Pre-Pricing Prospectus contains in all material respects the same description of the foregoing matters as will be contained in the Basic Prospectus, including the information incorporated by reference therein up to and through the date of this Agreement);

(oo) except as disclosed in the Disclosure Package and the Prospectus, the Partnership (i) does not have any material lending or other relationship with any bank or lending affiliate of an Underwriter and (ii) does not intend to use any of the proceeds from the sale of the Offered Units hereunder to repay any outstanding debt owed to any affiliate of an Underwriter;

(pp) the Subsidiaries listed on Annex A attached hereto are the only “significant subsidiaries” of the Partnership as of December 31, 2013 (as defined by Rule 1-02 of Regulation S-X); and

(qq) subsequent to the respective dates as of which information is given in the Registration Statement (as such information may have been superseded by a subsequent filing with the Commission), the Pre-Pricing Prospectuses, the Prospectus and the Permitted Free Writing Prospectuses, if any, in each case excluding any amendments or supplements to the foregoing made after the execution of this Agreement, there has not been (i) any material adverse change, or any development involving a prospective material adverse change, in the business, properties, management, financial condition or results of operations of the Partnership and the Subsidiaries taken as a whole, except for the sale of the Offered Units and the application of net proceeds thereof, (ii) any transaction which is material to the Partnership and the Subsidiaries, taken as a whole, except for the sale of the Offered Units and the application of net proceeds thereof, (iii) any obligation or liability, direct or contingent (including any off-balance sheet obligations), incurred by the Partnership or any Subsidiary, which is material to the Partnership and the Subsidiaries, taken as a whole, except for the sale of the Offered Units and the application of net proceeds thereof and issuances of commercial paper notes and any drawdowns under the Credit Agreement, (iv) any change in the capitalization or outstanding indebtedness of the Partnership or any Subsidiaries, except for the sale of the Offered Units and the application of net proceeds thereof and any

issuances of commercial paper notes and drawdowns under the Credit Agreement, or (v) any dividend or distribution of any kind declared, paid or made on the capital units of the Partnership or any Subsidiary.

In addition, any certificate signed by or on behalf of the Partnership and delivered to the Underwriters or counsel for the Underwriters in connection with the offering of the Offered Units shall be deemed to be a representation and warranty by the Partnership, as to matters covered thereby, to each Underwriter.

(a) to furnish such information as may be required and otherwise to cooperate in qualifying the Offered Units for offering and sale under the securities or blue sky laws of such states or other jurisdictions as you may designate and to maintain such qualifications in effect so long as you may reasonably request for the distribution of the Offered Units; provided, however, that the Partnership shall not be required to qualify as a foreign corporation or to consent to the service of process under the laws of any such jurisdiction (except service of process with respect to the offering and sale of the Offered Units); and to promptly advise you of the receipt by the Partnership of any notification with respect to the suspension of the qualification of the Offered Units for offer or sale in any jurisdiction or the initiation or threatening of any proceeding for such purpose;

(b) to make available to the Underwriters in New York City, as soon as practicable after this Agreement becomes effective, and thereafter from time to time to furnish to the Underwriters, as many copies of the Prospectus (or of the Prospectus as amended or supplemented if the Partnership shall have made any amendments or supplements thereto after the effective date of the Registration Statement) as the Underwriters may reasonably request for the purposes contemplated by the Act; in case any Underwriter is required to deliver (whether physically or through compliance with Rule 172 under the Act or any similar rule), in connection with the sale of the Offered Units, a prospectus after the nine-month period referred to in Section 10(a)(3) of the Act, or after the time a post-effective amendment to the Registration Statement is required pursuant to Item 512(a) of Regulation S-K under the Act, the Partnership will prepare, at its expense, promptly upon request such amendment or amendments to the Registration Statement and the Prospectus as may be necessary to permit compliance with the requirements of Section 10(a)(3) of the Act or Item 512(a) of Regulation S-K under the Act, as the case may be;

(c) if, at the time this Agreement is executed and delivered, it is necessary or appropriate for a post-effective amendment to the Registration Statement to be filed with the Commission and become effective before the Offered Units may be sold, the Partnership will use its reasonable best efforts to cause such post-effective amendment or such Registration Statement to be filed and become effective, and will pay any applicable fees in accordance with the Act, as soon as possible; and the Partnership will advise you promptly and, if requested by you, will confirm such advice in writing, (i) when such post-effective amendment or such Registration Statement has become effective, and (ii) if Rule 430A under the Act is used, when the Prospectus is filed with the Commission

pursuant to Rule 424(b) under the Act (which the Partnership agrees to file in a timely manner in accordance with such Rules);

(d) if, at any time during the period when a prospectus is required by the Act to be delivered (whether physically or through compliance with Rule 172 under the Act or any similar rule) in connection with any sale of Offered Units, the Registration Statement shall cease to comply with the requirements of the Act with respect to eligibility for the use of the form on which the Registration Statement was filed with the Commission or the Registration Statement shall cease to be an “automatic shelf registration statement” (as defined in Rule 405 under the Act) or the Partnership shall have received, from the Commission, a notice, pursuant to Rule 401(g)(2), of objection to the use of the form on which the Registration Statement was filed with the Commission, to (i) promptly notify you, (ii) promptly file with the Commission a new registration statement under the Act, relating to the Offered Units, or a post-effective amendment to the Registration Statement, which new registration statement or post-effective amendment shall comply with the requirements of the Act and shall be in a form reasonably satisfactory to you, (iii) use its reasonable best efforts to cause such new registration statement or post-effective amendment to become effective under the Act as soon as practicable, (iv) promptly notify you of such effectiveness and (v) take all other action necessary or appropriate to permit the public offering and sale of the Offered Units to continue as contemplated in the Prospectus; all references herein to the Registration Statement shall be deemed to include each such new registration statement or post-effective amendment, if any;

(e) if the third anniversary of the initial effective date of the Registration Statement (within the meaning of Rule 415(a)(5) under the Act) shall occur at any time during the period when a prospectus is required by the Act to be delivered (whether physically or through compliance with Rule 172 under the Act or any similar rule) in connection with any sale of Offered Units, to file with the Commission, prior to such third anniversary, a new registration statement under the Act relating to the Offered Units, which new registration statement shall comply with the requirements of the Act (including, without limitation, Rule 415(a)(6) under the Act) and shall be in a form reasonably satisfactory to you; such new registration statement shall constitute an “automatic shelf registration statement” (as defined in Rule 405 under the Act); provided, however, that if the Partnership is not then eligible to file an “automatic shelf registration statement” (as defined in Rule 405 under the Act), then such new registration statement need not constitute an “automatic shelf registration statement” (as defined in Rule 405 under the Act), but the Partnership shall use its reasonable best efforts to cause such new registration statement to become effective under the Act as soon as practicable, but in any event within 180 days after such third anniversary and promptly notify you of such effectiveness; the Partnership shall take all other action necessary or appropriate to permit the public offering and sale of the Offered Units to continue as contemplated in the Prospectus; all references herein to the Registration Statement shall be deemed to include each such new registration statement, if any;

(f) to advise you promptly, confirming such advice in writing, of any request by the Commission for amendments or supplements to the Registration Statement, any

Pre-Pricing Prospectus, the Prospectus or any Permitted Free Writing Prospectus or for additional information with respect thereto, or of notice of institution of proceedings for, or the entry of a stop order, suspending the effectiveness of the Registration Statement and, if the Commission should enter a stop order suspending the effectiveness of the Registration Statement, to use its reasonable best efforts to obtain the lifting or removal of such order as soon as possible; to advise you promptly of any proposal to amend or supplement the Registration Statement, any Pre-Pricing Prospectus or the Prospectus, and to provide you and Underwriters’ counsel copies of any such documents for review and comment a reasonable amount of time prior to any proposed filing and to file no such amendment or supplement to which you shall reasonably object in writing, unless, (i) in the judgment of counsel to the Partnership, such filing is required by applicable law or (ii) is advisable in furtherance of a Commission request;

(g) subject to Section 4(f) hereof, to file promptly all reports and documents and any preliminary or definitive proxy or information statement required to be filed by the Partnership with the Commission in order to comply with the Exchange Act for so long as a prospectus is required by the Act to be delivered (whether physically or through compliance with Rule 172 under the Act or any similar rule) in connection with any sale of Offered Units; and, for 30 days from the date hereof so long as the Underwriters have informed the Partnership that they have not completed their distribution of the Offered Units, to provide you, for your review and comment, with a copy of such reports and statements and other documents to be filed by the Partnership pursuant to Section 13, 14 or 15(d) of the Exchange Act during such period a reasonable amount of time prior to any proposed filing, and to file no such report, statement or document to which you shall have reasonably objected in writing; and to promptly notify you of such filing;

(h) to pay the fees applicable to the Registration Statement in connection with the offering of the Offered Units within the time required by Rule 456(b)(1)(i) under the Act (without reliance on the proviso to Rule 456(b)(1)(i) under the Act) and in compliance with Rule 456(b) and Rule 457(r) under the Act;

(i) to advise the Underwriters promptly of the happening of any event within the period during which a prospectus is required by the Act to be delivered (whether physically or through compliance with Rule 172 under the Act or any similar rule) in connection with any sale of Offered Units, which event could require the making of any change in the Prospectus then being used so that the Prospectus would not include an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they are made, not misleading, and to advise the Underwriters promptly if, during such period, it shall become necessary to amend or supplement the Prospectus to cause the Prospectus to comply with the requirements of the Act, and, in each case, during such time, subject to Section 4(f) hereof, to prepare and furnish, at the Partnership’s expense, to the Underwriters promptly such amendments or supplements to such Prospectus as may be necessary to reflect any such change or to effect such compliance;

(j) to make generally available to its security holders, and to deliver to you, an earnings statement of the Partnership (which will satisfy the provisions of Section

11(a) of the Act) covering a period of twelve months beginning after the effective date of the Registration Statement (as defined in Rule 158(c) under the Act) as soon as is reasonably practicable after the termination of such twelve-month period but in any case not later than May 10, 2015, which may be satisfied through the filing with the Commission of reports required under the Exchange Act;

(k) to furnish to you upon request prior to the time of purchase and any additional time of purchase, as the case may be, but not later than two business days prior thereto, a copy of the latest available unaudited interim and monthly consolidated financial statements, if any, of the Partnership and the Subsidiaries which have been read by the Partnership’s independent registered public accountants, as stated in their letter to be furnished pursuant to Section 6(d) hereof;

(l) to apply the net proceeds from the sale of the Offered Units in the manner set forth under the caption “Use of Proceeds” in the Prospectus Supplement;

(m) to pay all costs, expenses, fees and taxes in connection with (i) the preparation and filing of the Registration Statement, each Basic Prospectus, each Pre-Pricing Prospectus, the Prospectus Supplement, the Prospectus, each Permitted Free Writing Prospectus and any amendments or supplements thereto, and the printing and furnishing of copies of each thereof to the Underwriters and to dealers (including costs of mailing and shipment), (ii) the registration, issue, sale and delivery of the Offered Units including any stock or transfer taxes and stamp or similar duties payable upon the sale, issuance or delivery of the Offered Units to the Underwriters, (iii) the producing, word processing and/or printing of this Agreement, any Agreement Among Underwriters, any dealer agreements, any Powers of Attorney and any closing documents (including compilations thereof) and the reproduction and/or printing and furnishing of copies of each thereof to the Underwriters and (except closing documents) to dealers (including costs of mailing and shipment), (iv) the qualification of the Offered Units for offering and sale under state laws and the determination of their eligibility for investment under state law (including the reasonable legal fees and filing fees and other disbursements of counsel for the Underwriters) and the printing and furnishing of copies of any blue sky surveys or legal investment surveys to the Underwriters and to dealers, (v) any listing of the Offered Units on any securities exchange or qualification of the Offered Units for quotation on the NYSE and any registration thereof under the Exchange Act, (vi) any filing for review of the public offering of the Offered Units by the FINRA, including the reasonable legal fees and filing fees and other disbursements of counsel to the Underwriters relating to FINRA matters, (vii) the fees and disbursements of any transfer agent or registrar for the Offered Units, (viii) the costs and expenses of the Partnership relating to presentations or meetings undertaken in connection with the marketing of the offering and sale of the Offered Units to prospective investors and the Underwriters’ sales forces, including, without limitation, expenses associated with the production of road show slides and graphics, fees and expenses of any consultants engaged in connection with the road show presentations, travel, lodging and other expenses incurred by the officers of the Partnership and any such consultants, and (ix) the performance of the Partnership’s other obligations hereunder;

(n) to comply with Rule 433(d) under the Act (without reliance on Rule 164(b) under the Act) and with Rule 433(g) under the Act;

(o) beginning on the date hereof and ending on, and including, the date that is 45 days after the date of the Prospectus Supplement (the “Lock-Up Period”), without the prior written consent of Merrill Lynch, Pierce, Fenner & Smith Incorporated, not to (i) issue, sell, offer to sell, contract or agree to sell, hypothecate, pledge, grant any option to purchase or otherwise dispose of or agree to dispose of, directly or indirectly, or establish or increase a put equivalent position or liquidate or decrease a call equivalent position within the meaning of Section 16 of the Exchange Act and the rules and regulations of the Commission promulgated thereunder, with respect to, any Units or any other securities of the Partnership that are substantially similar to Units, or any securities convertible into or exchangeable or exercisable for, or any warrants or other rights to purchase, the foregoing; (ii) file or cause to become effective a registration statement under the Act relating to the offer and sale of any Units or any other securities of the Partnership that are substantially similar to Units, or any securities convertible into or exchangeable or exercisable for, or any warrants or other rights to purchase, the foregoing; (iii) enter into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of Units or any other securities of the Partnership that are substantially similar to Units, or any securities convertible into or exchangeable or exercisable for, or any warrants or other rights to purchase, the foregoing, whether any such transaction is to be settled by delivery of Units or such other securities, in cash or otherwise or (iv) publicly announce an intention to effect any transaction specified in clause (i), (ii) or (iii), except, in each case, for any of the foregoing in connection with (A) the registration of the offer and sale of the Offered Units as contemplated by this Agreement; (B) issuances of Units upon the exercise of options or warrants disclosed as outstanding in the Registration Statement (excluding the exhibits thereto), each Pre-Pricing Prospectus and the Prospectus; (C) sales of Units to ONEOK, Inc.; (D) the issue of Units in connection with the acquisition of or investment in other businesses that does not in the aggregate exceed 15% of the total Units outstanding and, provided that the recipient of such Units agrees in writing to the restrictions imposed by this Section 4(o) and (E) the issue of Units in connection with the “at the market” offering launched on January 23, 2013;

(p) not, at any time at or after the execution of this Agreement, to, directly or indirectly, offer or sell any Offered Units by means of any “prospectus” (within the meaning of the Act), or use any “prospectus” (within the meaning of the Act) in connection with the offer or sale of the Offered Units, in each case other than the Prospectus;

(q) not to, and to cause the Subsidiaries not to, take, directly or indirectly, any action designed, or which will constitute, or has constituted, or might reasonably be expected to cause or result in the stabilization or manipulation of the price of any security of the Partnership to facilitate the sale or resale of the Offered Units;

(r) to use its best efforts to cause the Offered Units to be listed on the NYSE; and, as of the date hereof, the Partnership expects to maintain the listing of the Units, including the Offered Units, on the NYSE; and

(s) to maintain a transfer agent and, if necessary under the jurisdiction of formation of the Partnership, a registrar for the Units for so long as the Units remain outstanding.

5. Reimbursement of Underwriters’ Expenses. If the Offered Units are not delivered for any reason other than the termination of this Agreement pursuant to the fifth paragraph of Section 8 hereof, the termination of this Agreement pursuant to any of (A), (C), (D) or (E) of subsection (2) of the second paragraph of Section 7 hereof or the default by one or more of the Underwriters in its or their respective obligations hereunder, the Partnership shall, in addition to paying the amounts described in Section 4(m) hereof, reimburse the Underwriters for all of their reasonable out-of-pocket expenses, including the reasonable fees and disbursements of their counsel.

6. Conditions of Underwriters’ Obligations. The several obligations of the Underwriters hereunder are subject to the accuracy of the representations and warranties on the part of the Partnership on the date hereof, at the time of purchase and, if applicable, at each additional time of purchase, the performance by the Partnership of its obligations hereunder and to the following additional conditions precedent:

(a) The Partnership shall furnish to you at the time of purchase and, if applicable, at the additional time of purchase, an opinion of Fried, Frank, Harris, Shriver & Jacobson LLP, counsel for the Partnership, addressed to the Underwriters, and dated the time of purchase or such additional time of purchase, as the case may be, with executed copies for each of the other Underwriters, in substantially the form set forth in Exhibit B hereto.

(b) The Partnership shall furnish to you at the time of purchase and, if applicable, at the additional time of purchase, an opinion of Gable & Gotwals, A Professional Corporation, counsel for the Partnership, addressed to the Underwriters, and dated the time of purchase or the additional time of purchase, as the case may be, with executed copies for each of the other Underwriters, in substantially the form set forth in Exhibit C hereto.

(c) The Partnership shall furnish to you at the time of purchase and, if applicable, at the additional time of purchase, an opinion of Andrews Kurth LLP, tax counsel for the Partnership, addressed to the Underwriters, and dated the time of purchase or the additional time of purchase, as the case may be, with executed copies for each of the other Underwriters, in substantially the form set forth in Exhibit D hereto.

(d) You shall have received from PricewaterhouseCoopers LLP letters dated, respectively, the date of this Agreement, the time of purchase and, if applicable, the additional time of purchase, and addressed to the Underwriters (with executed copies for each of the Underwriters) in the forms satisfactory to the Representatives and

PricewaterhouseCoopers LLP, which letters shall cover certain financial disclosures contained in the Registration Statement, the Pre-Pricing Prospectuses, the Prospectus and the Permitted Free Writing Prospectuses, if any.

(e) You shall have received at the time of purchase and, if applicable, at the additional time of purchase, the favorable opinion of Shearman & Sterling LLP, counsel for the Underwriters, dated the time of purchase or the additional time of purchase, as the case may be, in form and substance reasonably satisfactory to the Representatives.

(f) No Prospectus or amendment or supplement to the Registration Statement or the Prospectus shall have been filed to which you shall have objected in writing.

(g) The Registration Statement shall have been filed and shall have become effective under the Act. The Prospectus Supplement shall have been filed with the Commission pursuant to Rule 424(b) under the Act at or before 5:30 P.M., New York City time, on the second full business day after the date of this Agreement (or such earlier time as may be required under the Act).

(h) Prior to and at the time of purchase, and, if applicable, the additional time of purchase, (i) no stop order with respect to the effectiveness of the Registration Statement shall have been issued under the Act or proceedings initiated under Section 8(d) or 8(e) of the Act; (ii) the Registration Statement and all amendments thereto shall not contain an untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading; (iii) none of the Pre-Pricing Prospectuses or the Prospectus, and no amendment or supplement thereto, shall include an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they are made, not misleading; (iv) no Disclosure Package, and no amendment or supplement thereto, shall include an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they are made, not misleading; and (v) none of the Permitted Free Writing Prospectuses, if any, shall include an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they are made, not misleading.

(i) The Partnership will, at the time of purchase and, if applicable, at the additional time of purchase, deliver to you a certificate of the Partnership, signed by the Chairman of the Board or the President and Chief Executive Officer and the principal financial or accounting officer of the General Partner, dated the time of purchase or the additional time of purchase, as the case may be, in the form attached as Exhibit E hereto.

(j) You shall have received each of the signed Lock-Up Agreements referred to in Section 3(u) hereof, and each such Lock-Up Agreement shall be in full force and effect at the time of purchase and the additional time of purchase, as the case may be.

(k) The Partnership shall have furnished to you such other documents and certificates as to the accuracy and completeness of any statement in the Registration

Statement, any Pre-Pricing Prospectus, the Prospectus or any Permitted Free Writing Prospectus as of the time of purchase and, if applicable, the additional time of purchase, as you may reasonably request.

(l) The Offered Units shall have been approved for listing on the NYSE, subject only to notice of issuance at or prior to the time of purchase or the additional time of purchase, as the case may be. The Partnership shall not have received any notice regarding the delisting of the Units from the NYSE.

(m) The FINRA shall not have raised any objection with respect to the fairness or reasonableness of the underwriting, or other arrangements of the transactions, contemplated hereby.

7. Effective Date of Agreement; Termination. This Agreement shall become effective when the parties hereto have executed and delivered this Agreement.

The obligations of the several Underwriters hereunder shall be subject to termination in the absolute discretion of the Representatives, if (1) since the time of execution of this Agreement or the earlier respective dates as of which information is given in the Registration Statement, the Pre-Pricing Prospectuses, the Prospectus and the Permitted Free Writing Prospectuses, if any, there has been any change or any development involving a prospective change in the business, properties, management, financial condition or results of operations of the Partnership and the Subsidiaries taken as a whole, the effect of which change or development is, in the sole judgment of the Representatives, so material and adverse as to make it impractical or inadvisable to proceed with the public offering or the delivery of the Offered Units on the terms and in the manner contemplated in the Registration Statement, the Pre-Pricing Prospectuses, the Prospectus and the Permitted Free Writing Prospectuses, if any, or (2) since the time of execution of this Agreement, there shall have occurred: (A) a suspension or material limitation in trading in securities generally on the NYSE; (B) a suspension or material limitation in trading in the Partnership’s securities on the NYSE; (C) a general moratorium on commercial banking activities declared by either federal or New York State authorities or a material disruption in commercial banking or securities settlement or clearance services in the United States; (D) an outbreak or escalation of hostilities or acts of terrorism involving the United States or a declaration by the United States of a national emergency or war; or (E) any other calamity or crisis or any change in financial, political or economic conditions in the United States or elsewhere, if the effect of any such event specified in clause (D) or (E), in the sole judgment of the Representatives, makes it impractical or inadvisable to proceed with the public offering, sale or the delivery of the Offered Units on the terms and in the manner contemplated in the Registration Statement, the Pre-Pricing Prospectuses, the Prospectus and the Permitted Free Writing Prospectuses, if any, or (3) since the time of execution of this Agreement, there shall have occurred any downgrading, or any notice or announcement shall have been given or made of: (A) any intended or potential downgrading or (B) any watch, review or possible change that does not indicate an affirmation or improvement in the rating accorded any securities of the Partnership by any “nationally recognized statistical rating organization,” as that term is defined in Section 3(a)(62) of the Exchange Act.

If the Representatives elect to terminate this Agreement as provided in this Section 7, the Partnership and each other Underwriter shall be notified promptly in writing.

If the sale to the Underwriters of the Offered Units, as contemplated by this Agreement, is not carried out by the Underwriters for any reason permitted under this Agreement, or if such sale is not carried out because the Partnership shall be unable to comply with any of the terms of this Agreement, the Partnership shall not be under any obligation or liability under this Agreement (except to the extent provided in Sections 4(m), 5 and 9 hereof), and the Underwriters shall be under no obligation or liability to the Partnership under this Agreement (except to the extent provided in Section 9 hereof) or to one another hereunder.

8. Increase in Underwriters’ Commitments. Subject to Sections 6 and 7 hereof, if any Underwriter shall default in its obligation to take up and pay for the Firm Units to be purchased by it hereunder (otherwise than for a failure of a condition set forth in Section 6 hereof or a reason sufficient to justify the termination of this Agreement under the provisions of Section 7 hereof) and if the number of Firm Units which all Underwriters so defaulting shall have agreed but failed to take up and pay for does not exceed 10% of the total number of Firm Units, the non-defaulting Underwriters (including the Underwriters, if any, substituted in the manner set forth below) shall take up and pay for (in addition to the aggregate number of Firm Units they are obligated to purchase pursuant to Section 1 hereof) the number of Firm Units agreed to be purchased by all such defaulting Underwriters, as hereinafter provided. Such Offered Units shall be taken up and paid for by such non-defaulting Underwriters in such amount or amounts as you may designate with the consent of each Underwriter so designated or, in the event no such designation is made, such Offered Units shall be taken up and paid for by all non-defaulting Underwriters pro rata in proportion to the aggregate number of Firm Units set forth opposite the names of such non-defaulting Underwriters in Schedule A.

Without relieving any defaulting Underwriter from its obligations hereunder, the Partnership agrees with the non-defaulting Underwriters that they will not sell any Firm Units hereunder unless all of the Firm Units are purchased by the Underwriters (or by substituted Underwriters selected by you with the approval of the Partnership or selected by the Partnership with your approval).

If a new Underwriter or Underwriters are substituted by the Underwriters or by the Partnership for a defaulting Underwriter or Underwriters in accordance with the foregoing provision, the Partnership or you shall have the right to postpone the time of purchase for a period not exceeding five business days in order that any necessary changes in the Registration Statement and the Prospectus and other documents may be effected.

The term “Underwriter” as used in this Agreement shall refer to and include any Underwriter substituted under this Section 8 with like effect as if such substituted Underwriter had originally been named in Schedule A hereto.

If the aggregate number of Firm Units which the defaulting Underwriter or Underwriters agreed to purchase exceeds 10% of the total number of Firm Units which all Underwriters agreed to purchase hereunder, and if neither the non-defaulting Underwriters nor the Partnership shall make arrangements within the five business day period stated above for the

purchase of all the Firm Units which the defaulting Underwriter or Underwriters agreed to purchase hereunder, this Agreement shall terminate without further act or deed and without any liability on the part of the Partnership to any Underwriter and without any liability on the part of any non-defaulting Underwriter to the Partnership. Nothing in this paragraph, and no action taken hereunder, shall relieve any defaulting Underwriter from liability in respect of any default of such Underwriter under this Agreement.

(a) The Partnership agrees to indemnify and hold harmless each Underwriter, the directors, officers, employees, affiliates and agents of each Underwriter and each person who controls any Underwriter within the meaning of either the Act or the Exchange Act against any and all losses, claims, damages or liabilities, joint or several, to which they or any of them may become subject under the Act, the Exchange Act or other U.S. Federal or state statutory law or regulation, at common law or otherwise, insofar as such losses, claims, damages or liabilities (or actions in respect thereof) arise out of or are based (i) upon any untrue statement or alleged untrue statement of a material fact contained in the Registration Statement, or in any amendment thereof or supplement thereto, or arise out of or are based upon the omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading; or (ii) upon any untrue statement or alleged untrue statement of a material fact contained in the Basic Prospectus, any Pre-Pricing Prospectus or any other preliminary prospectus supplement relating to the Offered Units, the Prospectus Supplement, the Prospectus, in any Permitted Free Writing Prospectus, in any “issuer information” (as defined in Rule 433 under the Act) of the Partnership or in any Prospectus together with any combination of one or more of the Permitted Free Writing Prospectuses, if any, or in any amendment thereof or supplement thereto, or arise out of or are based upon the omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein, in light of the circumstances under which they were made, not misleading, and agrees to reimburse each such indemnified party, as incurred, for any legal or other expenses reasonably incurred by them in connection with investigating or defending any such loss, claim, damage, liability or action; provided, however, that the Partnership will not be liable in any such case to the extent that any such loss, claim, damage or liability arises out of or is based upon any such untrue statement or alleged untrue statement or omission or alleged omission made therein in reliance upon and in conformity with written information furnished to the Partnership by or on behalf of any Underwriter through the Representatives specifically for inclusion therein. This indemnity agreement will be in addition to any liability which the Partnership may otherwise have.

(b) Each Underwriter, severally and not jointly, agrees to indemnify and hold harmless the Partnership, each of the respective directors and officers of the General Partner and each person who controls the Partnership within the meaning of either the Act or the Exchange Act, to the same extent as the foregoing indemnity from the Partnership to each Underwriter, but only with reference to written information relating to such Underwriter furnished to the Partnership by or on behalf of such Underwriter through the Representatives specifically for inclusion in the documents referred to in the

foregoing indemnity. This indemnity agreement will be in addition to any liability which any Underwriter may otherwise have.

(c) Promptly after receipt by an indemnified party under this Section 9 of notice of the commencement of any action, such indemnified party will, if a claim in respect thereof is to be made against the indemnifying party under this Section 9, notify the indemnifying party in writing of the commencement thereof; but the failure so to notify the indemnifying party (i) will not relieve it from liability under paragraph (a) or (b) above unless and only to the extent it did not otherwise learn of such action and such failure results in the forfeiture by the indemnifying party of substantial rights and defenses and (ii) will not, in any event, relieve the indemnifying party from any obligations to any indemnified party other than the indemnification obligation provided in paragraph (a) or (b) above. The indemnifying party shall be entitled to appoint counsel of the indemnifying party’s choice at the indemnifying party’s expense to represent the indemnified party in any action for which indemnification is sought (in which case the indemnifying party shall not thereafter be responsible for the fees and expenses of any separate counsel retained by the indemnified party or parties except as set forth below); provided, however, that such counsel shall be satisfactory to the indemnified party. Notwithstanding the indemnifying party’s election to appoint counsel to represent the indemnified party in an action, the indemnified party shall have the right to employ separate counsel (including local counsel), and the indemnifying party shall bear the reasonable fees, costs and expenses of such separate counsel if (i) the use of counsel chosen by the indemnifying party to represent the indemnified party would present such counsel with a conflict of interest, (ii) the actual or potential defendants in, or targets of, any such action include both the indemnified party and the indemnifying party and the indemnified party shall have reasonably concluded that there may be legal defenses available to it and/or other indemnified parties which are different from or additional to those available to the indemnifying party, (iii) the indemnifying party shall not have employed counsel satisfactory to the indemnified party to represent the indemnified party within a reasonable time after notice of the institution of such action or (iv) the indemnifying party shall authorize the indemnified party to employ separate counsel at the expense of the indemnifying party. The indemnifying party shall not be liable for any settlement of any pending or threatened claim, action, suit or proceeding in respect of which indemnification or contribution may be sought hereunder (whether or not the indemnified parties are actual or potential parties to such claim or action) effected without its written consent, but, if settled with its written consent, such indemnifying party agrees to indemnify and hold harmless the indemnified party or parties from and against any loss or liability by reason of such settlement. Notwithstanding the foregoing sentence, if at any time an indemnified party shall have requested an indemnifying party to reimburse the indemnified party for fees and expenses of counsel as contemplated by the second sentence of this Section 9(c), then the indemnifying party agrees that it shall be liable for any settlement of any Proceeding effected without its written consent if (i) such settlement is entered into more than 60 business days after receipt by such indemnifying party of the aforesaid request, (ii) such indemnifying party shall not have fully reimbursed the indemnified party in accordance with such request prior to the date of such settlement and (iii) such indemnified party shall have given the indemnifying party at least 30 days’ prior notice of its intention to settle. An indemnifying party will

not, without the prior written consent of the indemnified parties, settle, compromise or consent to the entry of any judgment with respect to any pending or threatened claim, action, suit or proceeding in respect of which indemnification or contribution may be sought hereunder (whether or not the indemnified parties are actual or potential parties to such claim or action) unless (i) such settlement, compromise or consent includes an unconditional release of each indemnified party from all liability arising out of such claim, action, suit or proceeding and (ii) does not include a statement as to or an admission of fault, culpability or a failure to act by or on behalf of any indemnified party.

(d) In the event that the indemnity provided in paragraph (a) or (b) of this Section 9 is unavailable to or insufficient to hold harmless an indemnified party for any reason, but is otherwise applicable in accordance with its terms, the Partnership and the Underwriters severally agree to contribute to the aggregate losses, claims, damages and liabilities (including legal or other expenses reasonably incurred in connection with investigating or defending same) (collectively, “Losses”) to which the Partnership and one or more of the Underwriters may be subject in such proportion as is appropriate to reflect the relative benefits received by the Partnership on the one hand and by the Underwriters on the other from the offering of the Offered Units; provided, however, that in no case shall any Underwriter (except as may be provided in any agreement among underwriters relating to the offering of the Offered Units) be responsible for any amount in excess of the underwriting discount or commission applicable to the Offered Units purchased by such Underwriter hereunder. If the allocation provided by the immediately preceding sentence is unavailable for any reason, the Partnership and the Underwriters severally shall contribute in such proportion as is appropriate to reflect not only such relative benefits but also the relative fault of the Partnership, on the one hand, and of the Underwriters, on the other, in connection with the statements or omissions which resulted in such Losses, as well as any other relevant equitable considerations. Benefits received by the Partnership shall be deemed to be equal to the total net proceeds from the offering (before deducting expenses) received by it, and benefits received by the Underwriters shall be deemed to be equal to the total underwriting discounts and commissions, in each case as set forth on the cover page of the Prospectus. Relative fault shall be determined by reference to, among other things, whether any untrue or any alleged untrue statement of a material fact or the omission or alleged omission to state a material fact relates to information provided by the Partnership, on the one hand, or the Underwriters, on the other, the intent of the parties and their relative knowledge, access to information and opportunity to correct or prevent such untrue statement or omission. The Partnership and the Underwriters agree that it would not be just and equitable if contribution were determined by pro rata allocation or any other method of allocation which does not take account of the equitable considerations referred to above. Notwithstanding the provisions of this paragraph (d), no person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Act) shall be entitled to contribution from any person who was not guilty of such fraudulent misrepresentation. For purposes of this Section 9, each person who controls an Underwriter within the meaning of either the Act or the Exchange Act and each director, officer, employee, affiliate and agent of an Underwriter shall have the same rights to contribution as such Underwriter, and each person who controls the Partnership within the meaning of either the Act or the Exchange Act and each officer and director of the General Partner shall have the same rights to contribution

as the Partnership, subject in each case to the applicable terms and conditions of this paragraph (d).

10. Information Furnished by the Underwriters. The statements set forth under the subheading “Price Stabilization, Short Positions” under the caption “Underwriting” in the Prospectus, only insofar as such statements relate to over-allotment and stabilization activities that may be undertaken by the Underwriters constitute the only information furnished by or on behalf of the Underwriters, as such information is referred to in Sections 3 and 9 hereof.

11. Representations and Indemnities to Survive. The indemnity and contribution agreements contained in Section 9 hereof and the covenants, warranties and representations of the Partnership contained in this Agreement shall remain in full force and effect regardless of any investigation made by or on behalf of any Underwriter, its partners, directors or officers or any person (including each partner, officer or director of such person) who controls any Underwriter within the meaning of Section 15 of the Act or Section 20 of the Exchange Act, or by or on behalf of the Partnership, each of the directors or officers of the General Partner or any person who controls the Partnership within the meaning of Section 15 of the Act or Section 20 of the Exchange Act, and shall survive any termination of this Agreement or the issuance and delivery of the Offered Units. The Partnership and each Underwriter agree promptly to notify each other of the commencement of any Proceeding against it and, in the case of the Partnership, against any of the General Partner’s officers or directors in connection with the issuance and sale of the Offered Units, or in connection with the Registration Statement, any Basic Prospectus, any Pre-Pricing Prospectus, the Prospectus or any Permitted Free Writing Prospectus.

12. Notices. Except as otherwise herein provided, all statements, requests, notices and agreements shall be in writing or by telegram or facsimile and, if to the Underwriters, shall be sufficient in all respects if delivered or sent to Merrill Lynch, Pierce, Fenner & Smith Incorporated, One Bryant Park, New York, New York 10036, attention: Syndicate Department (facsimile: (646) 855-3073); and, if to the Partnership, shall be sufficient in all respects if delivered or sent to the Partnership at the offices of the Partnership at ONEOK Partners, L.P., 100 W. 5^th Street, Tulsa, OK 74103, Attention: General Counsel, (facsimile: (918) 588-7971).

13. Governing Law; Construction. This Agreement and any claim, counterclaim or dispute of any kind or nature whatsoever arising out of or in any way relating to this Agreement (“Claim”), directly or indirectly, shall be governed by, and construed in accordance with, the laws of the State of New York. The section headings in this Agreement have been inserted as a matter of convenience of reference and are not a part of this Agreement.

14. Submission to Jurisdiction. Except as set forth below, no Claim may be commenced, prosecuted or continued in any court other than the courts of the State of New York located in the City and County of New York or in the United States District Court for the Southern District of New York, which courts shall have jurisdiction over the adjudication of such matters, and the Partnership consents to the jurisdiction of such courts and personal service with respect thereto. The Partnership hereby consents to personal jurisdiction, service and venue in any court in which any Claim arising out of or in any way relating to this Agreement is brought by any third party against any Underwriter or any indemnified party. Each Underwriter and the Partnership (on its behalf and, to the extent permitted by applicable law, on behalf of its

unitholders and affiliates) waive all right to trial by jury in any action, proceeding or counterclaim (whether based upon contract, tort or otherwise) in any way arising out of or relating to this Agreement. The Partnership agrees that a final judgment in any such action, proceeding or counterclaim brought in any such court shall be conclusive and binding upon the Partnership and may be enforced in any other courts to the jurisdiction of which the Partnership is or may be subject, by suit upon such judgment.

15. Parties at Interest. The Agreement herein set forth has been and is made solely for the benefit of the Underwriters and the Partnership and to the extent provided in Section 9 hereof the controlling persons, partners, directors and officers referred to in such Section, and their respective successors, assigns, heirs, personal representatives and executors and administrators. No other person, partnership, association or corporation (including a purchaser, as such purchaser, from any of the Underwriters) shall acquire or have any right under or by virtue of this Agreement.

16. No Fiduciary Relationship. The Partnership hereby acknowledges that the Underwriters are acting solely as underwriters in connection with the purchase and sale of the Partnership’s securities. The Partnership further acknowledges that the Underwriters are acting pursuant to a contractual relationship created solely by this Agreement entered into on an arm’s length basis, and in no event do the parties intend that the Underwriters act or be responsible as a fiduciary to the Partnership, its management, unitholders or creditors or any other person in connection with any activity that the Underwriters may undertake or have undertaken in furtherance of the purchase and sale of the Partnership’s securities, either before or after the date hereof. The Underwriters hereby expressly disclaim any fiduciary or similar obligations to the Partnership, either in connection with the transactions contemplated by this Agreement or any matters leading up to such transactions, and the Partnership hereby confirms its understanding and agreement to that effect. The Partnership and the Underwriters agree that they are each responsible for making their own independent judgments with respect to any such transactions and that any opinions or views expressed by the Underwriters to the Partnership regarding such transactions, including, but not limited to, any opinions or views with respect to the price or market for the Partnership’s securities, do not constitute advice or recommendations to the Partnership. The Partnership hereby waives and releases, to the fullest extent permitted by law, any claims that the Partnership may have against the Underwriters with respect to any breach or alleged breach of any fiduciary or similar duty to the Partnership in connection with the transactions contemplated by this Agreement or any matters leading up to such transactions.

17. Counterparts. This Agreement may be signed in one or more counterparts, each of which, when executed and delivered, shall constitute an original and all of which together shall constitute one and the same agreement.

18. Successors and Assigns. This Agreement shall be binding upon the Underwriters and the Partnership and their successors and assigns and the indemnified persons referred to in Section 9 hereof and any successor or assign of any substantial portion of the Partnership’s and any of the Underwriters’ respective businesses and/or assets.

If the foregoing correctly sets forth the understanding between the Partnership and the several Underwriters, please so indicate in the space provided below for that purpose, whereupon this Agreement and your acceptance shall constitute a binding agreement between the Partnership and the Underwriters, severally.


Very truly yours,

ONEOK Partners, L.P.

By:		ONEOK Partners GP, L.L.C., its general partner

By:		/s/ Derek S. Reiners
		Name: Derek S. Reiners
		Title: Senior Vice President, Chief
		Financial Officer and Treasurer


MERRILL LYNCH, PIERCE, FENNER & SMITH
INCORPORATED

By:		/s/ Karl F. Schlopy
		Name: Karl F. Schlopy
		Title: Managing Director


BARCLAYS CAPITAL INC.

By:		/s/ Victoria Hale
		Name: Victoria Hale
		Title: Vice President


MORGAN STANLEY & CO. LLC

By:		/s/ Alice Vilma
		Name: Alice Vilma
		Title: Executive Director


UBS SECURITIES LLC

By:		/s/ John Nesland
		Name: John Nesland
		Title: Managing Director

By:		/s/ Ephraim Musokwa
		Name: Ephraim Musokwa
		Title: Managing Director


WELLS FARGO SECURITIES, LLC

By:		/s/ Elizabeth DiChiaro
		Name: Elizabeth DiChiaro
		Title: Managing Director


Underwriter	Number of Firm Units
Merrill Lynch, Pierce, Fenner & Smith Incorporated		1,360,040
Barclays Capital Inc.		1,360,040
Morgan Stanley & Co. LLC		1,360,040
UBS Securities LLC		1,360,040
Wells Fargo Securities, LLC		1,360,040
Citigroup Global Markets Inc.		847,000
Deutsche Bank Securities Inc.		847,000
Goldman, Sachs & Co.		847,000
J.P. Morgan Securities LLC		847,000
RBC Capital Markets, LLC		847,000
Jefferies LLC		484,000
Robert W. Baird & Co. Incorporated		145,200
BB&T Capital Markets, a division of BB&T Securities, LLC		145,200
Global Hunter Securities, LLC		145,200
Oppenheimer & Co. Inc.		145,200

Total		12,100,000


Common units offered to the public:		12,100,000 common units

Option to purchase additional common units:		1,815,000 common units; option to purchase additional common units from ONEOK Partners, L.P.

Price per common unit to the public:		$52.94