Underwriting Agreement

1. Introductory. Koppers Holdings Inc., a Pennsylvania corporation (the “Company”), proposes to issue and sell 8,700,000 shares of its Common Stock, par value $0.01 per share (the “Securities”), and the shareholders listed in Schedule A hereto (the “Selling Shareholders”) propose severally to sell an aggregate of 1,300,000 outstanding shares of Securities (such 10,000,000 shares of Securities being hereinafter referred to as the “Firm Securities”), to the Underwriters (as defined below), for whom Credit Suisse Securities (USA) LLC (“CSS”) and UBS Securities LLC are acting as representatives (the “Representatives”). The Selling Shareholders also propose to sell to the Underwriters, at the option of the Underwriters, not more than 1,500,000 additional outstanding shares of the Company’s Securities, as set forth below (such 1,500,000 additional shares being hereinafter referred to as the “Optional Securities”). The Firm Securities and the Optional Securities are herein collectively called the “Offered Securities”. As part of the offering contemplated by this Agreement, CSS (the “Designated Underwriter”) has agreed to reserve out of the Firm Securities purchased by it under this Agreement up to 500,000 shares, or 5% of the Firm Securities, for sale to the Company’s directors, officers, employees and other parties identified by the Company (collectively, the “Participants”), as set forth in the Prospectus (as defined herein) under the heading “Underwriting” (the “Directed Share Program”). The Firm Securities to be sold by the Designated Underwriter pursuant to the Directed Share Program (the “Directed Shares”) will be sold by the Designated Underwriter pursuant to this Agreement at the public offering price. Any Directed Shares not subscribed for by the end of the business day on which this Agreement is executed will be offered to the public by the Underwriters as set forth in the Prospectus. The Company and the Selling Shareholders hereby agree with the several Underwriters named in Schedule B hereto (“Underwriters”) as follows:

2. Representations and Warranties of the Company and the Selling Shareholders. (a) The Company represents and warrants to, and agrees with, the several Underwriters that:

(i) A registration statement (No. 333-128250) relating to the Offered Securities, including a form of prospectus, has been filed with the United States Securities and Exchange Commission (“Commission”) and either (A) has been declared effective under the Securities Act of 1933, as amended (the “Act”), and is not proposed to be amended or (B) is proposed to be amended by amendment or post-effective amendment. If such registration statement (the “initial registration statement”) has been declared effective, either (A) an additional registration statement (the “additional registration statement”) relating to the Offered Securities may have been filed with the Commission pursuant to Rule 462(b) (“Rule 462(b)”) under the Act and, if so filed, has become effective upon filing pursuant to such Rule and the Offered Securities all have been duly registered under the Act pursuant to the initial registration statement and, if applicable, the additional registration statement or (B) such an additional registration statement is proposed to be filed with the Commission pursuant to Rule 462(b) and will become effective upon filing pursuant to such Rule and upon such filing the Offered Securities will all have been duly registered under the Act pursuant to the initial registration statement and such additional registration statement. If the Company does not propose to amend

the initial registration statement or if an additional registration statement has been filed and the Company does not propose to amend it, and if any post-effective amendment to either such registration statement has been filed with the Commission prior to the execution and delivery of this Agreement, the most recent amendment (if any) to each such registration statement has been declared effective by the Commission or has become effective upon filing pursuant to Rule 462(c) (“Rule 462(c)”) under the Act or, in the case of the additional registration statement, Rule 462(b). For purposes of this Agreement, “Effective Time” with respect to the initial registration statement or, if filed prior to the execution and delivery of this Agreement, the additional registration statement means (A) if the Company has advised the Representatives that it does not propose to amend such registration statement, the date and time as of which such registration statement, or the most recent post-effective amendment thereto (if any) filed prior to the execution and delivery of this Agreement, was declared effective by the Commission or has become effective upon filing pursuant to Rule 462(c), or (B) if the Company has advised the Representatives that it proposes to file an amendment or post-effective amendment to such registration statement, the date and time as of which such registration statement, as amended by such amendment or post-effective amendment, as the case may be, is declared effective by the Commission. If an additional registration statement has not been filed prior to the execution and delivery of this Agreement but the Company has advised the Representatives that it proposes to file one, “Effective Time” with respect to such additional registration statement means the date and time as of which such registration statement is filed and becomes effective pursuant to Rule 462(b). “Effective Date” with respect to the initial registration statement or the additional registration statement (if any) means the date of the Effective Time thereof. The initial registration statement, as amended at its Effective Time, including all information contained in the additional registration statement (if any) and deemed to be a part of the initial registration statement as of the Effective Time of the additional registration statement pursuant to the General Instructions of the Form on which it is filed and including all information (if any) deemed to be a part of the initial registration statement as of its Effective Time pursuant to Rule 430A(b) (“Rule 430A(b)”) under the Act, is hereinafter referred to as the “Initial Registration Statement”. The additional registration statement, as amended at its Effective Time, including the contents of the initial registration statement incorporated by reference therein and including all information (if any) deemed to be a part of the additional registration statement as of its Effective Time pursuant to Rule 430A(b), is hereinafter referred to as the “Additional Registration Statement”. The Initial Registration Statement and the Additional Registration Statement are hereinafter referred to collectively as the “Registration Statements” and individually as a “Registration Statement”. “Registration Statement” without reference to a time means the Registration Statement as of its Effective Time. “Registration Statement” as of any time means the initial registration statement and any additional registration statement in the form then filed with the Commission, including any amendment thereto and any prospectus deemed or retroactively deemed to be a part thereof that has not been superseded or modified. For purposes of the previous sentence, information contained in a form of prospectus or prospectus supplement that is deemed retroactively to be a part of the Registration Statement pursuant to Rule 430A shall be considered to be included in the Registration Statement as of the time specified in Rule 430A. “Statutory Prospectus” as of any time means the prospectus included in the Registration Statement immediately prior to that time, including any prospectus deemed to be a part thereof that has not been superseded or modified. For purposes of the preceding sentence, information contained in a form of prospectus that is deemed retroactively to be a part of the Registration Statement pursuant to Rule 430A shall be considered to be included in the Statutory Prospectus as of the actual time that form of prospectus is filed with the Commission pursuant to Rule 424(b) (“Rule 424(b)”) under the Act. “Prospectus” means the Statutory Prospectus that discloses the public offering price and other final terms of the Offered Securities and otherwise satisfies Section 10(a) of the Act. “Issuer Free Writing Prospectus” means any “issuer free writing prospectus,” as defined in Rule 433, relating to the Offered Securities in the form filed or required to be filed with the Commission or, if not required to be filed, in the form retained in the Company’s records pursuant to Rule 433(g). “General Use Issuer Free Writing Prospectus” means any Issuer Free Writing Prospectus that is intended for general distribution to prospective investors, as evidenced by its being specified in a schedule to this Agreement. “Limited Use Issuer Free Writing Prospectus” means any Issuer Free Writing Prospectus that is not a General Use Issuer Free Writing Prospectus. “Applicable Time” means [·:00 [a/p]m] (Eastern time) on the date of this Agreement.

omit to state any material fact required to be stated therein or necessary to make the statements therein not misleading, (B) on the Effective Date of the Additional Registration Statement (if any), each Registration Statement conformed or will conform, in all material respects to the requirements of the Act and the Rules and Regulations and did not include, or will not include, any untrue statement of a material fact and did not omit, or will not omit, to state any material fact required to be stated therein or necessary to make the statements therein not misleading, and (C) on the date of this Agreement, the Initial Registration Statement and, if the Effective Time of the Additional Registration Statement is prior to the execution and delivery of this Agreement, the Additional Registration Statement each conforms, and at the time of filing of the Prospectus pursuant to Rule 424(b) or (if no such filing is required) at the Effective Date of the Additional Registration Statement in which the Prospectus is included, and at each Closing Date, each Registration Statement and the Prospectus will conform, in all material respects to the requirements of the Act and the Rules and Regulations, and neither of such documents includes, or will include, any untrue statement of a material fact or omits, or will omit, to state any material fact required to be stated therein or necessary to make the statements therein and in the case of the Prospectus, in light of the circumstances under which they were made, not misleading. If the Effective Time of the Initial Registration Statement is subsequent to the execution and delivery of this Agreement: on the Effective Date of the Initial Registration Statement, the Initial Registration Statement and the Prospectus will conform in all respects to the requirements of the Act and the Rules and Regulations, neither of such documents will include any untrue statement of a material fact or will omit to state any material fact required to be stated therein or necessary to make the statements therein and in the case of the Prospectus, in light of the circumstances under which they were made, not misleading, and no Additional Registration Statement has been or will be filed. The two preceding sentences do not apply to statements in or omissions from a Registration Statement or the Prospectus based upon written information furnished to the Company by any Underwriter through the Representatives specifically for use therein, it being understood and agreed that the only such information is that described as such in Section 8(c) hereof.

(iii) As of the Applicable Time, neither (a) the General Use Issuer Free Writing Prospectus(es) issued at or prior to the Applicable Time, the Statutory Prospectus, and [the documents attached to this Agreement], all considered together (collectively, the “General Disclosure Package”), nor (b) any individual Limited Use Issuer Free Writing Prospectus, when considered together with the General Disclosure Package, included any untrue statement of a material fact or omitted to state any material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading. The preceding sentence does not apply to statements in or omissions from any prospectus included in the Registration Statement or any Issuer Free Writing Prospectus in reliance upon and in conformity with written information furnished to the Company by any Underwriter through the Representatives specifically for use therein, it being understood and agreed that the only such information furnished by any Underwriter consists of the information described as such in Section 8(c) hereof.

(iv) Each Issuer Free Writing Prospectus, as of its issue date and at all subsequent times through the completion of the public offer and sale of the Offered Securities or until any earlier date that the Company notified or notifies CSS as described in the next sentence, did not, does not and will not include any information that conflicted, conflicts or will conflict with the information then contained in the Registration Statement. If at any time following issuance of an Issuer Free Writing Prospectus there occurred or occurs an event or development as a result of which such Issuer Free Writing Prospectus conflicted or would conflict with the information then contained in the Registration Statement or included or would include an untrue statement of a material fact or omitted or would omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances prevailing at that subsequent time, not misleading, (a) the Company has promptly notified or will promptly notify the representatives and (b) the Company has promptly amended or will promptly amend or supplement such Issuer Free Writing Prospectus to eliminate or correct such conflict, untrue statement or omission. The foregoing two sentences do not apply to statements in or

omissions from any Issuer Free Writing Prospectus in reliance upon and in conformity with written information furnished to the Company by any Underwriter through the Representatives specifically for use therein, it being understood and agreed that the only such information furnished by any Underwriter consists of the information described as such in Section 8(c) hereof.

(v) The Company has been duly incorporated and is an existing corporation in good standing under the laws of the Commonwealth of Pennsylvania, with corporate power and authority to own its properties and conduct its business as described in the General Disclosure Package; and the Company is duly qualified to do business as a foreign corporation in good standing in all other jurisdictions in which its ownership or lease of property or the conduct of its business requires such qualification except where the failure to be so qualified or in good standing would not, individually or in the aggregate, have a material adverse effect on the condition (financial or otherwise), business, properties, prospects or results of operations of the Company and its subsidiaries taken as a whole (“Material Adverse Effect”).

(vi) Each subsidiary of the Company has been duly incorporated or formed and is an existing corporation or other entity in good standing under the laws of the jurisdiction of its incorporation or formation, with corporate power and authority to own its properties and conduct its business as described in the General Disclosure Package; and each subsidiary of the Company is duly qualified to do business as a foreign corporation or other entity in good standing in all other jurisdictions in which its ownership or lease of property or the conduct of its business requires such qualification, except where the failure to be so qualified or to be in good standing would not, individually or in the aggregate, result in a Material Adverse Effect; all of the issued and outstanding capital stock or other ownership interest of each subsidiary of the Company has been duly authorized and validly issued and is fully paid and nonassessable; and the capital stock or other ownership interest of each subsidiary owned by the Company, directly or through subsidiaries, is owned free from liens, encumbrances and defects other than liens and encumbrances pursuant to Koppers Inc.’s senior secured credit facility and senior secured notes. The entities listed on Schedule C are the only subsidiaries, direct or indirect, of the Company.

(vii) The Offered Securities and all other outstanding shares of capital stock of the Company have been duly authorized and have been (or, in the case of the Offered Securities, when issued and paid for in accordance with the term of this Agreement will be) validly issued, fully paid and nonassessable and conform, in all material respects, to the description thereof contained in the Prospectus; and the shareholders of the Company have no preemptive rights with respect to the Securities.

(viii) As of the date of this Agreement, the Company has an authorized and outstanding capitalization as set forth under the heading “Actual” in the section of the Registration Statement and the Prospectus entitled “Capitalization” and, as of each Closing Date hereinafter mentioned, the Company shall have an authorized and outstanding capitalization as set forth under the heading “As Adjusted” in the section of the Registration Statement and the Prospectus entitled “Capitalization”.

(ix) Except as disclosed in the General Disclosure Package, there are no contracts, agreements or understandings between the Company or any of its subsidiaries and any person that would give rise to a valid claim against the Company, any of its subsidiaries or any Underwriter for a brokerage commission, finder’s fee or other like payment in connection with this offering.

(x) Except as disclosed in the General Disclosure Package, there are no contracts, agreements or understandings between the Company or any of its subsidiaries and any person granting such person the right to require the Company or any of its subsidiaries to file a registration statement under the Act with respect to any securities of the Company or any of its subsidiaries or to require the Company or any of its subsidiaries to include such securities in the securities registered pursuant to a Registration Statement or in any securities being registered pursuant to any other registration statement filed by the Company under the Act.

(xi) The Securities have been approved for listing subject to notice of issuance on The New York Stock Exchange.

(xii) No consent, approval, authorization, or order of, or filing with, any governmental agency or body or any court is required to be obtained or made by the Company for the consummation of the transactions contemplated by this Agreement in connection with the sale of the Offered Securities, except such as have been obtained and made under the Act and such as may be required under state securities laws.

(xiii) The execution, delivery and performance of this Agreement, and the consummation of the transactions herein contemplated, will not result in a breach or violation of any of the terms and provisions of, or constitute a default under (A) any statute, any rule, regulation or order of any governmental agency or body or any court, domestic or foreign, having jurisdiction over the Company or any subsidiary of the Company or any of their properties, (B) any agreement or instrument to which the Company or any such subsidiary is a party or by which the Company or any such subsidiary is bound or to which any of the properties of the Company or any such subsidiary is subject, or (C) the charter, by-laws or other organizational document of the Company or any such subsidiary, except in the case of clause (B), for such breaches, violations or defaults that would not, individually or in the aggregate, have a Material Adverse Effect.

(xiv) This Agreement has been duly authorized, executed and delivered by the Company.

(xv) Except as disclosed in the General Disclosure Package, the Company and its subsidiaries have good and marketable title to all real properties and all other properties and assets owned by them, in each case free from liens, encumbrances and defects that would materially affect the value thereof or materially interfere with the use made or to be made thereof by them; and except as disclosed in the General Disclosure Package, the Company and its subsidiaries hold any leased real or personal property under valid and enforceable leases with no exceptions that would materially interfere with the use made or to be made thereof by them.

(xvi) The Company and its subsidiaries possess adequate certificates, authorities or permits issued by appropriate governmental agencies or bodies necessary to conduct the business now operated by them, except for such certificates, authorities or permits the lack of which would not, individually or in the aggregate, have a Material Adverse Effect, and have not received any notice of proceedings relating to the revocation or modification of any such certificate, authority or permit that would, individually or in the aggregate, have a Material Adverse Effect.

(xvii) No labor dispute with the employees of the Company or any subsidiary exists or, to the knowledge of the Company, is imminent that would reasonably be expected to have a Material Adverse Effect.

(xviii) The Company and its subsidiaries own, possess, or can acquire on reasonable terms, adequate trademarks, trade names and other rights to inventions, know-how, patents, copyrights, confidential information and other intellectual property (collectively, “intellectual property rights”) necessary to conduct the business now operated by them, or presently employed by them, and have not received any notice of infringement of or conflict with asserted rights of others with respect to any intellectual property rights that would, individually or in the aggregate, have a Material Adverse Effect.

(xix) Except as specifically disclosed in the General Disclosure Package, the Company and its subsidiaries and their properties, assets and operations are in compliance with, and hold all permits, authorizations and approvals required under, Environmental Laws (as defined below), except to the extent that failure so to comply or to hold such permits, authorizations or approvals would not be reasonably expected to, individually or in the aggregate, have a Material Adverse Effect; except as disclosed in the General Disclosure Package, there are no past, present or, to the Company’s knowledge, reasonably anticipated future events, conditions, circumstances, activities, practices, actions, omissions or plans that could reasonably be expected to give rise to any material costs or liabilities to the Company or its subsidiaries under, or to materially interfere with or prevent compliance by the Company or its subsidiaries with, Environmental Laws; except as disclosed in the General Disclosure Package, neither the Company nor any of its subsidiaries (i) is the subject of any investigation, (ii) has received any notice or claim, (iii) is a party to or affected by any pending or threatened action, suit or proceeding, (iv) is bound by any judgment, decree or order or (v) has entered into any agreement, in each case relating to any alleged violation of any Environmental Law or an alleged liability arising from or relating to any actual or alleged release or threatened release or cleanup at any location of any Hazardous Materials (as defined below) except as would not, individually or in the aggregate, if determined adversely, reasonably be expected to have a Material Adverse Effect (as used herein, “Environmental Law” means any federal, state, local or foreign law, statute, ordinance, rule, regulation, order, decree, judgment, injunction, permit, license, authorization or other binding requirement, or common law, relating to health,

safety or the protection, cleanup or restoration of the environment or natural resources, including those relating to the distribution, processing, generation, treatment, storage, disposal, transportation, other handling or release or threatened release of, or exposure to, Hazardous Materials, and “Hazardous Materials” means any material (including, without limitation, pollutants, contaminants, hazardous or toxic substances or wastes) that is regulated by or may give rise to liability under any Environmental Law).

(xx) In the ordinary course of its business, the Company and each of its subsidiaries conducts a periodic review of the effect of the Environmental Laws on their respective business, operations and properties, for the purpose of identifying and evaluating associated material costs and liabilities (including, without limitation, any capital or operating expenditures required for cleanup, other remedial activities or compliance with the Environmental Laws or any permit, license or approval issued under Environmental Laws and any potential liabilities to third parties).

(xxi) Except as disclosed in the General Disclosure Package, there are no pending actions, suits or proceedings against or affecting the Company, any of its subsidiaries or any of their respective properties that would, individually or in the aggregate, have a Material Adverse Effect, or would materially and adversely affect the ability of the Company to perform its obligations under this Agreement, or which are otherwise material in the context of the sale of the Offered Securities; and no such actions, suits or proceedings are, to the Company’s knowledge, threatened or contemplated.

(xxii) The consolidated financial statements of the Company included in each Registration Statement and the General Disclosure Package present fairly in all material respects the financial position of the Company and its consolidated subsidiaries as of the dates shown and their results of operations and cash flows for the periods shown, and, except as otherwise disclosed in the General Disclosure Package, such financial statements have been prepared in conformity with the generally accepted accounting principles in the United States applied on a consistent basis; and all disclosures contained in the Registration Statement or the General Disclosure Package regarding “non-GAAP financial measures” (as such term is defined by the rules and regulations of the Commission) comply with Regulation G of the Exchange Act and Item 10 of Regulation S-K under the Act, to the extent applicable.

(xxiii) Except as disclosed in the General Disclosure Package, since the date of the latest audited financial statements included in the General Disclosure Package there has been no material adverse change, nor any development or event involving a prospective material adverse change, in the condition (financial or other), business, properties or results of operations of the Company and its subsidiaries taken as a whole, and, except as disclosed in or contemplated by the General Disclosure Package, there has been no dividend or distribution of any kind declared, paid or made by the Company on any class of its capital stock.

(xxiv) The Company is subject to the reporting requirements of either Section 13 or Section 15(d) of the Securities Exchange Act of 1934 and files reports with the Commission on the Electronic Data Gathering, Analysis, and Retrieval (EDGAR) system.

(xxv) The Company is not and, after giving effect to the offering and sale of the Offered Securities and the application of the proceeds thereof as described in the General Disclosure Package, will not be, an “investment company” as defined in the Investment Company Act of 1940.

(xxvi) The Company has not offered, or caused the Underwriters to offer, any Offered Securities to any person pursuant to the Directed Share Program with the specific intent to unlawfully influence (i) a customer or supplier of the Company to alter the customer’s or supplier’s level or type of business with the Company or (ii) a trade journalist or publication to write or publish favorable information about the Company or its products.

(xxvii) Ernst & Young LLP, who have reviewed certain financial statements of the Company and its consolidated subsidiaries included in each Registration Statement and the Prospectus, are independent public accountants with respect to the Company within the meaning of the Act and the applicable published rules and regulations thereunder.

(xxviii) The Company and each of its subsidiaries makes and keeps accurate books and records and maintains a system of internal accounting controls sufficient to provide reasonable assurance that (i) transactions are executed in accordance with management’s general or specific authorization;

(ii) transactions are recorded as necessary to permit preparation of financial statements in conformity with generally accepted accounting principles and to maintain accountability for assets; (iii) access to assets is permitted only in accordance with management’s general or specific authorization; and (iv) the recorded accountability for assets is compared with existing assets at reasonable intervals and appropriate action is taken with respect to any differences.

(xxix) The Company has established and maintains disclosure controls and procedures (as such term is defined in Rule 13a-15 and 15d-15 under the Exchange Act); such disclosure controls and procedures are designed to ensure that material information relating to the Company, including its consolidated subsidiaries, is made known to the Company’s Chief Executive Officer and its Chief Financial Officer by others within those entities, and such disclosure controls and procedures are effective to perform the functions for which they were established; the Company’s auditors and the Audit Committee of the Board of Directors have been advised, based on the Company’s most recent evaluation of such disclosure controls and procedures, of: (i) any significant deficiencies in the design or operation of internal controls which could adversely affect the Company’s ability to record, process, summarize, and report financial data; and (ii) any fraud, whether or not material, that involves management or other employees who have a role in the Company’s internal controls; any material weaknesses in internal controls have been identified for the Company’s auditors; except as disclosed in the Registration Statement and General Disclosure Package, since the date of the most recent evaluation of such disclosure controls and procedures, there have been no significant changes in internal controls or in other factors that could significantly affect internal controls, including any corrective actions with regard to significant deficiencies and material weaknesses; and the Company is taking all necessary actions to ensure that, upon and at all times after effectiveness of the Registration Statement, except as disclosed in the Registration Statement and General Disclosure Package, the Company and its officers and directors, in their capacities as such, will be in compliance in all material respects with the provisions of the Sarbanes-Oxley Act of 2002 (the “Sarbanes-Oxley Act”) and the rules and regulations promulgated in connection therewith, including provisions with respect to “internal control over financial reporting” (as such term is defined in Rules 13a-15 and 15d-15 under the Act), which are applicable at such time to the Company.

(xxx) The Company has provided you true, correct, and complete copies of all documentation pertaining to any extension of credit in the form of a personal loan made, directly or indirectly, by the Company to any director or executive officer of the Company, or to any family member or affiliate of any director or executive officer of the Company; and since July 30, 2002, the Company has not, directly or indirectly, including through any subsidiary: (i) extended credit, arranged to extend credit, or renewed any extension of credit, in the form of a personal loan, to or for any director or executive officer of the Company, or to or for any family member or affiliate of any director or executive officer of the Company; or (ii) made any material modification, including any renewal thereof, to any term of any personal loan to any director or executive officer of the Company, or any family member or affiliate of any director or executive officer, which loan was outstanding on July 30, 2002.

(xxxi) (A) On or before the date hereof, “lock-up” agreements, each substantially in the form of Exhibit E hereto (“Lock-Up Agreements”), relating to sales and certain other dispositions of shares of Securities or certain other securities, have been executed and delivered to the Representatives by all officers and directors of the Company and the shareholders and option-holders listed on Schedule E as of the date hereof, and all such agreements are in full force and effect; and (B) the persons listed on Schedule D hereto are all of the shareholders, optionholders, officers and directors of the Company as of the date hereof.

In addition, any certificate signed by any officer of the Company and delivered to the Underwriters or counsel for the Underwriters in connection with the offering of the Securities shall be deemed to be a representation and warranty by the Company or Subsidiary, as the case may be, as to matters covered thereby, to each Underwriter.

(b) Each Selling Shareholder, severally and not jointly, represents and warrants to, and agrees with, the several Underwriters that:

(i) Each Selling Shareholder has and on each Closing Date hereinafter mentioned will have valid and unencumbered title to the Offered Securities to be delivered by such Selling Shareholder on such Closing Date and full right, power and authority to enter into this Agreement and to sell, assign, transfer and deliver the Offered Securities to be delivered by such Selling Shareholder on such Closing Date hereunder; and upon the delivery of and payment for the Offered Securities on each Closing Date hereunder the several Underwriters will acquire valid and unencumbered title to the Offered Securities to be delivered by such Selling Shareholder on such Closing Date.

(ii) If the Effective Time of the Initial Registration Statement is prior to the execution and delivery of this Agreement: (A) on the Effective Date of the Initial Registration Statement, the Initial Registration Statement conformed in all material respects to the requirements of the Act and the Rules and Regulations and did not include any untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary to make the statements therein not misleading, (B) on the Effective Date of the Additional Registration Statement (if any), each Registration Statement conformed, or will conform, in all material respects to the requirements of the Act and the Rules and Regulations did not include, or will not include, any untrue statement of a material fact and did not omit, or will not omit, to state any material fact required to be stated therein or necessary to make the statements therein not misleading, and (C) on the date of this Agreement, the Initial Registration Statement and, if the Effective Time of the Additional Registration Statement is prior to the execution and delivery of this Agreement, the Additional Registration Statement each conforms, and at the time of filing of the Prospectus pursuant to Rule 424(b) or (if no such filing is required) at the Effective Date of the Additional Registration Statement in which the Prospectus is included, each Registration Statement and the Prospectus will conform, in all material respects to the requirements of the Act and the Rules and Regulations, and neither of such documents includes, or will include, any untrue statement of a material fact or omits, or will omit, to state any material fact required to be stated therein or necessary to make the statements therein not misleading. If the Effective Time of the Initial Registration Statement is subsequent to the execution and delivery of this Agreement: on the Effective Date of the Initial Registration Statement, the Initial Registration Statement and the Prospectus will conform in all material respects to the requirements of the Act and the Rules and Regulations, neither of such documents will include any untrue statement of a material fact or will omit to state any material fact required to be stated therein or necessary to make the statements therein not misleading. The two preceding sentences apply only to the extent that any statements in or omissions from a Registration Statement or the Prospectus are based on written information furnished to the Company by such Selling Shareholder specifically for use therein.

(iii) Except as disclosed in the Prospectus, there are no contracts, agreements or understandings between such Selling Shareholder and any person that would give rise to a valid claim against such Selling Shareholder or any Underwriter for a brokerage commission, finder’s fee or other like payment in connection with this offering.

3. Purchase, Sale and Delivery of Offered Securities. On the basis of the representations, warranties and agreements herein contained, but subject to the terms and conditions herein set forth, the Company and each Selling Shareholder agree, severally and not jointly, to sell to each Underwriter, and each Underwriter agrees, severally and not jointly, to purchase from the Company and each Selling Shareholder, at a purchase price of $[ ] per share, that number of Firm Securities (rounded up or down, as determined by CSS in its discretion, in order to avoid fractions) obtained by multiplying 8,700,000 Firm Securities in the case of the Company and the number of Firm Securities set forth opposite the name of such Selling Shareholder in Schedule A hereto, in the case of a Selling Shareholder, in each case by a fraction the numerator of which is the number of Firm Securities set forth opposite the name of such Underwriter in Schedule B hereto and the denominator of which is the total number of Firm Securities.

The Offered Securities to be sold by the Selling Shareholders hereunder have been placed in custody, for delivery under this Agreement, under Custody Agreements made with [ ], as custodian (“Custodian”). Each Selling Shareholder agrees that the shares held in custody for the Selling Shareholders under such Custody Agreements are subject to the interests of the Underwriters hereunder, that the arrangements made by the Selling Shareholders for such custody are to that extent irrevocable, and that the obligations of the Selling Shareholders hereunder shall not be terminated by operation of law, whether by the death of any individual Selling Shareholder or the occurrence of any other event, or in the case of a trust, by the death of any trustee or trustees or the termination of such trust. If any individual Selling Shareholder or any such trustee or trustees should die, or if any other such event should occur, or if any of such trusts should terminate, before the delivery of the Offered Securities hereunder, certificates for such Offered Securities shall be delivered by the Custodian in accordance with the terms and conditions of this Agreement as if such death or other event or termination had not occurred, regardless of whether or not the Custodian shall have received notice of such death or other event or termination.

The Company and the Custodian will deliver the Firm Securities to the Representatives for the accounts of the Underwriters against payment of the purchase price in Federal (same day) funds by official bank check or checks

or wire transfer to an account at a bank acceptable to CSS drawn to the order of Koppers Holdings Inc., in the case of 8,700,000 shares of Firm Securities and [ ] in the case of 1,300,000 shares of Firm Securities, at the office of Cravath, Swaine & Moore LLP, at [ ] A.M., New York time, on [ ], 2006, or at such other time not later than seven full business days thereafter as CSS and the Company determine, such time being herein referred to as the “First Closing Date”. For purposes of Rule 15c6-1 under the Securities Exchange Act of 1934, the First Closing Date (if later than the otherwise applicable settlement date) shall be the settlement date for payment of funds and delivery of securities for all the Offered Securities sold pursuant to the offering. The certificates for the Firm Securities so to be delivered will be in definitive form, in such denominations and registered in such names as CSS requests and will be made available for checking and packaging at the office of Cravath, Swaine & Moore LLP at least 24 hours prior to the First Closing Date.

In addition, upon written notice from CSS given to the Company and the Selling Shareholders from time to time not more than 30 days subsequent to the date of the Prospectus, the Underwriters may purchase all or less than all of the Optional Securities at the purchase price per Security to be paid for the Firm Securities. The Selling Shareholders agree, severally and not jointly, to sell to the Underwriters the respective numbers of Optional Securities obtained by multiplying the number of Optional Securities specified in such notice by a fraction the numerator of which is the number of shares set forth opposite the names of such Selling Shareholders in Schedule A hereto under the caption “Number of Optional Securities to be Sold” in the case of the Selling Shareholders and the denominator of which is the total number of Optional Securities (subject to adjustment by CSS to eliminate fractions). Such Optional Securities shall be purchased from each Selling Shareholder for the account of each Underwriter in the same proportion as the number of Firm Securities set forth opposite such Underwriter’s name bears to the total number of Firm Securities (subject to adjustment by CSS to eliminate fractions) and may be purchased by the Underwriters only for the purpose of covering over-allotments made in connection with the sale of the Firm Securities. No Optional Securities shall be sold or delivered unless the Firm Securities previously have been, or simultaneously are, sold and delivered. The right to purchase the Optional Securities or any portion thereof may be exercised from time to time and to the extent not previously exercised may be surrendered and terminated at any time upon notice by CSS to the Company and the Selling Shareholders.

Each time for the delivery of and payment for the Optional Securities, being herein referred to as an “Optional Closing Date”, which may be the First Closing Date (the First Closing Date and each Optional Closing Date, if any, being sometimes referred to as a “Closing Date”), shall be determined by CSS but shall be not later than five full business days after written notice of election to purchase Optional Securities is given. The Custodian will deliver the Optional Securities being purchased on each Optional Closing Date to the Representatives for the accounts of the several Underwriters, against payment of the purchase price therefor in Federal (same day) funds by official bank check or checks or wire transfer to an account at a bank acceptable to CSS drawn to the order of [ ] at the office of Cravath, Swaine & Moore LLP. Delivery of the Optional Securities shall be made through the facilities of The Depository Trust Company unless CSS shall otherwise instruct.

4. Offering by Underwriters. It is understood that the several Underwriters propose to offer the Offered Securities for sale to the public as set forth in the Prospectus.

5. Certain Agreements of the Company and the Selling Shareholders. (a) The Company agrees with the several Underwriters and the Selling Shareholders that:

(i) The Company has filed or will file each Statutory Prospectus pursuant to and in accordance with Rule 424(b)(1) (or, if applicable and consented to by CSS, subparagraph (4)) not later than the second business day following the earlier of the date it is first used or the date of this Agreement.

(ii) If the Effective Time of the Initial Registration Statement is prior to the execution and delivery of this Agreement, the Company will file the Prospectus with the Commission pursuant to and in accordance with subparagraph (1) (or, if applicable and if consented to by CSS, which consent shall not be unreasonably withheld or delayed, subparagraph (4)) of Rule 424(b) not later than the earlier of (A) the second business day following the execution and delivery of this Agreement or (B) the fifteenth business day after the Effective Date of the Initial Registration Statement. The Company will advise CSS promptly of any such filing pursuant to Rule 424(b). If the Effective Time of the Initial Registration Statement is prior to the execution and delivery of this Agreement and an additional registration statement is necessary to register a portion of the Offered Securities under the Act but the Effective Time thereof has not occurred as of such execution and delivery, the Company will file the additional registration statement or, if filed, will file a post-effective

amendment thereto with the Commission pursuant to and in accordance with Rule 462(b) on or prior to 10:00 P.M., New York time, on the date of this Agreement or, if earlier, on or prior to the time the Prospectus is printed and distributed to any Underwriter, or will make such filing at such later date as shall have been consented to by CSS, which consent shall not be unreasonably withheld or delayed.

(iii) The Company will advise the Representatives promptly of any proposal to amend or supplement the initial or any additional registration statement as filed or the related prospectus or the Initial Registration Statement, the Additional Registration Statement (if any) or any Statutory Prospectus and will not effect such amendment or supplementation without the Representative’s consent; and the Company will also advise the Representatives promptly of the effectiveness of each Registration Statement (if its Effective Time is subsequent to the execution and delivery of this Agreement) and of any amendment or supplementation of a Registration Statement or any Statutory Prospectus and of the institution by the Commission of any stop order proceedings in respect of a Registration Statement and will use its reasonable best efforts to prevent the issuance of any such stop order and to obtain as soon as possible its lifting, if issued.

(iv) If, at any time when a prospectus relating to the Offered Securities is (or but for the exemption in Rule 172 would be required to be) delivered under the Act in connection with sales by any Underwriter or dealer, any event occurs as a result of which the Prospectus as then amended or supplemented would include an untrue statement of a material fact or omit to state any material fact necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading, or if it is necessary at any time to amend the Prospectus to comply with the Act, the Company will promptly notify the Representatives of such event and will promptly prepare and file with the Commission, at its own expense, an amendment or supplement which will correct such statement or omission or an amendment which will effect such compliance. Neither the Representatives’ consent to, nor the Underwriters’ delivery of, any such amendment or supplement shall constitute a waiver of any of the conditions set forth in Section 7.

(v) As soon as practicable, but not later than the Availability Date (as defined below), the Company will make generally available to its securityholders an earnings statement covering a period of at least 12 months beginning after the Effective Date of the Initial Registration Statement (or, if later, the Effective Date of the Additional Registration Statement) which will satisfy the provisions of Section 11(a) of the Act. For the purpose of the preceding sentence, “Availability Date” means the 45th day after the end of the fourth fiscal quarter following the fiscal quarter that includes such Effective Date, except that, if such fourth fiscal quarter is the last quarter of the Company’s fiscal year, “Availability Date” means the 90th day after the end of such fourth fiscal quarter.

(vi) The Company will furnish to the Representatives copies of each Registration Statement (three of which will be signed and will include all exhibits), each related preliminary prospectus, and, so long as a prospectus relating to the Offered Securities is required to be delivered under the Act in connection with sales by any Underwriter or dealer, the Prospectus and all amendments and supplements to such documents, in each case in such quantities as CSS requests. The Prospectus shall be so furnished on or prior to 3:00 P.M., New York time, on the business day following the later of the execution and delivery of this Agreement or the Effective Time of the Initial Registration Statement. All other such documents shall be so furnished as soon as available. The Company and the Selling Shareholders will pay the expenses of printing and distributing to the Underwriters all such documents.

(vii) The Company will arrange for the qualification of the Offered Securities for sale under the laws of such jurisdictions as CSS designates and will continue such qualifications in effect so long as required for the distribution; provided, that the Company shall not be required to qualify as a foreign corporation in, or to take any action that would subject it to general consent to service of process or taxation in, any jurisdiction in which it is not now qualified or subject.

(viii) For the period specified below (the “Lock-Up Period”), the Company will not offer, sell, contract to sell, pledge or otherwise dispose of, directly or indirectly, or file with the Commission a registration statement under the Act relating to, any additional shares of its Securities or securities convertible into or exchangeable or exercisable for any shares of its Securities, or publicly disclose the intention to make any such offer, sale, pledge, disposition or filing, without the prior written consent of the Representatives, except (A) issuances of Securities pursuant to the conversion or exchange of convertible or exchangeable securities or the exercise of warrants or options, in each case outstanding on the date hereof, (B) grants of

employee stock options or restricted stock units pursuant to the terms of a plan in effect on the date hereof , (C) issuances of Securities pursuant to the exercise of such options or the exercise of any other employee stock options outstanding on the date hereof, (D) as consideration for acquisitions made by the Company, provided that no more than an aggregate of 10% of the number of shares of common stock outstanding as of the Closing Date are issued as consideration in connection with all such acquisitions and provided, further, that the recipients receiving common stock in connection with such acquisitions agree in writing with the Representatives to the restrictions in Exhibit E hereto and represent to the Representatives that they have not transferred to another, in whole or in part, any economic consequence of ownership of such shares of common stock prior to the consummation of such acquisition and (E) the filing of any registration statement on Form S-8 relating to securities that have been or may be issued pursuant to clause (B) above. The initial Lock-Up Period will commence on the date hereof and will continue and include the date 180 days after the date hereof or such earlier date that the Representatives consent to in writing; provided, however, that if (1) during the last 17 days of the initial Lock-Up Period, the Company releases earnings results or material news or a material event relating to the Company occurs or (2) prior to the expiration of the initial Lock-Up Period, the Company announces that it will release earnings results during the 16-day period beginning on the last day of the initial Lock-Up Period, then in each case the Lock-Up Period will be extended until the expiration of the 18-day period beginning on the date of release of the earnings results or the occurrence of the material news or material event, as applicable, unless the Representatives waive, in writing, such extension. The Company will provide the Representatives with notice of any announcement described in clause (2) of the preceding sentence that gives rise to an extension of the Lock-Up Period.

(ix) The Company will pay all reasonable expenses incident to the performance of the obligations of the Company and the Selling Shareholders, as the case may be, under this Agreement, for any filing fees and other expenses (including fees and disbursements of counsel) in connection with qualification of the Offered Securities for sale under the laws of such jurisdictions as CSS designates and the printing of memoranda relating thereto, for the filing fee incident to the review by the National Association of Securities Dealers, Inc. of the Offered Securities, for any travel expenses of the Company’s officers and employees and any other expenses of the Company in connection with attending or hosting meetings with prospective purchasers of the Offered Securities, including the cost of any aircraft chartered in connection with attending or hosting such meetings, for any transfer taxes on the sale by the Selling Shareholders of the Offered Securities to the Underwriters and for expenses incurred in distributing preliminary prospectuses and the Prospectus (including any amendments and supplements thereto) to the Underwriters and for expenses incurred for preparing, printing and distributing any Issuer Free Writing Prospectuses to investors or prospective investors. Except as expressly provided in this Agreement, the Underwriters shall pay their own costs and expenses in connection with the transactions contemplated hereby, including without limitation, the fees and expenses of their counsel.

(x) In connection with the Directed Share Program, the Company will ensure that the Directed Shares will be restricted to the extent required by the National Association of Securities Dealers, Inc. (the “NASD”) or the NASD rules from sale, transfer, assignment, pledge or hypothecation for a period of three months following the date of the effectiveness of the Registration Statement. The Designated Underwriter will notify the Company as to which Participants will need to be so restricted. The Company will direct the transfer agent to place stop transfer restrictions upon such securities for such period of time.

(xi) The Company will pay all reasonable fees and disbursements of counsel incurred by the Underwriters in connection with the Directed Share Program and stamp duties, similar taxes or duties or other taxes, if any, incurred by the Underwriters in connection with the Directed Share Program.

(b) Each Selling Shareholder agrees with the several Underwriters and the Company that:

(i) Each Selling Shareholder agrees during the Lock-Up Period not to offer, sell, contract to sell, pledge or otherwise dispose of, directly or indirectly, any additional shares of the Securities of the Company or securities convertible into or exchangeable or exercisable for any shares of Securities, enter into a transaction which would have the same effect, or enter into any swap, hedge or other arrangement that transfers, in whole or in part, any of the economic consequences of ownership of the Securities, whether any such aforementioned transaction is to be settled by delivery of the Securities or such other securities, in cash or otherwise, or publicly disclose the intention to make any such offer, sale, pledge or disposition, or enter into any such transaction, swap, hedge or other arrangement, without, in each case, the prior written consent of CSS, except if the Selling

Shareholder is a partnership, limited liability company or corporation, (1) transfers of Securities to an affiliate (as defined in Rule 405 of the Rules and Regulations) of such Selling Shareholder or (2) distributions by such Selling Shareholder to its partners, members or shareholders (including by way of redemption or liquidation); provided, however, that (y) each recipient of such Securities shall have, prior to any such transfer or distribution, entered into a written lock-up agreement that is identical in all material respects with this Section 5(b) and (z) no filing by any party (transferor or transferee) under the Securities Exchange Act of 1934, as amended, shall be required or voluntarily made in connection with such transfer or distribution. The initial Lock-Up Period will commence on the date hereof and will continue and include the date 180 days after the date hereof or such earlier date that CSS consents to in writing; provided, however, that if (1) during the last 17 days of the initial Lock-Up Period, the Company releases earnings results or material news or a material event relating to the Company occurs or (2) prior to the expiration of the initial Lock-up Period, the company announces that it will release earnings results during the 16-day period beginning on the last day of the initial Lock-Up Period, then in each case the Lock-Up Period will be extended until the expiration of the 18 day period beginning on the date of release of the earnings results or the occurrence of the material news or material event, as applicable, unless CSS waives, in writing, such extension.

6. Free Writing Prospectuses. The Company represents and agrees that, unless it obtains the prior consent of CSS, and each Underwriter represents and agrees that, unless it obtains the prior consent of the Company and CSS, it has not made and will not make any offer relating to the Offered Securities that would constitute an Issuer Free Writing Prospectus, or that would otherwise constitute a “free writing prospectus,” as defined in Rule 405, required to be filed with the Commission. Any such free writing prospectus consented to by the Company and CSS is hereinafter referred to as a “Permitted Free Writing Prospectus.” The Company represents that it has treated and agrees that it will treat each Permitted Free Writing Prospectus as an “issuer free writing prospectus,” as defined in Rule 433, and has complied and will comply with the requirements of Rules 164 and 433 applicable to any Permitted Free Writing Prospectus, including timely Commission filing where required, legending and record keeping.

7. Conditions of the Obligations of the Underwriters. The obligations of the several Underwriters to purchase and pay for the Firm Securities on the First Closing Date and the Optional Securities to be purchased on each Optional Closing Date will be subject to the accuracy of the representations and warranties on the part of the Company and the Selling Shareholders herein, to the accuracy of the statements of Company officers made pursuant to the provisions hereof, to the performance by the Company and the Selling Shareholders of their obligations hereunder and to the following additional conditions precedent:

(a) The Representatives shall have received a letter, dated the date of delivery thereof (which, if the Effective Time of the Initial Registration Statement is prior to the execution and delivery of this Agreement, shall be on or prior to the date of this Agreement or, if the Effective Time of the Initial Registration Statement is subsequent to the execution and delivery of this Agreement, shall be prior to the filing of the amendment or post-effective amendment to the registration statement to be filed shortly prior to such Effective Time), of Ernst & Young LLP confirming that they are independent public accountants within the meaning of the Act and the applicable published Rules and Regulations thereunder and substantially in the form of Exhibit A hereto.

(b) If the Effective Time of the Initial Registration Statement is not prior to the execution and delivery of this Agreement, such Effective Time shall have occurred not later than 10:00 P.M., New York time, on the date of this Agreement or such later date as shall have been consented to by CSS. If the Effective Time of the Additional Registration Statement (if any) is not prior to the execution and delivery of this Agreement, such Effective Time shall have occurred not later than 10:00 P.M., New York time, on the date of this Agreement or, if earlier, the time the Prospectus is printed and distributed to any Underwriter, or shall have occurred at such later date as shall have been consented to by CSS. If the Effective Time of the Initial Registration Statement is prior to the execution and delivery of this Agreement, the Prospectus shall have been filed with the Commission in accordance with the Rules and Regulations and Section 5(a)(ii) of this Agreement. Prior to such Closing Date, no stop order suspending the effectiveness of a Registration Statement shall have been issued and no proceedings for that purpose shall have been instituted or, to the knowledge of any Selling Shareholder, the Company or the Representatives, shall be contemplated by the Commission.

(c) Subsequent to the execution and delivery of this Agreement, there shall not have occurred (i) any change, or any development or event involving a prospective change, in the condition (financial or other), business, properties or results of operations of the Company and its subsidiaries taken as one enterprise which, in the

judgment of a majority in interest of the Underwriters including the Representatives, is material and adverse and makes it impractical or inadvisable to proceed with completion of the public offering or the sale of and payment for the Offered Securities; (ii) any downgrading in the rating of any debt securities or preferred stock of the Company by any “nationally recognized statistical rating organization” (as defined for purposes of Rule 436(g) under the Act), or any public announcement that any such organization has under surveillance or review its rating of any debt securities or preferred stock of the Company (other than an announcement with positive implications of a possible upgrading, and no implication of a possible downgrading, of such rating); (iii) any change in U.S. or international financial, political or economic conditions or currency exchange rates or exchange controls as would, in the judgment of a majority in interest of the Underwriters including the Representatives, be likely to prejudice materially the success of the proposed issue, sale or distribution of the Offered Securities, whether in the primary market or in respect of dealings in the secondary market; (iv) any material suspension or material limitation of trading in securities generally on the New York Stock Exchange, or any setting of minimum prices for trading on such exchange; (v) or any suspension of trading of any securities of the Company on any exchange or in the over-the-counter market; (vi) any banking moratorium declared by U.S. Federal or New York authorities; (vii) any major disruption of settlements of securities or clearance services in the United States or (viii) any attack on, outbreak or escalation of hostilities or act of terrorism involving the United States, any declaration of war by Congress or any other national or international calamity or emergency if, in the judgment of a majority in interest of the Underwriters including the Representatives, the effect of any such attack, outbreak, escalation, act, declaration, calamity or emergency makes it impractical or inadvisable to proceed with completion of the public offering or the sale of and payment for the Offered Securities.

(d) The Representatives shall have received an opinion and a letter, each dated such Closing Date, of Cahill Gordon & Reindel LLP, counsel for the Company, in the forms attached hereto as Exhibit B-1 and B-2.

(e) The Representatives shall have received an opinion, dated such Closing Date, of Reed Smith LLP, special Pennsylvania counsel for the Company, in the form attached hereto as Exhibit C.

(f) The Representatives shall have received (i) on or prior to the date hereof, the opinion contemplated in the Power of Attorney executed and delivered by each Selling Shareholder; (ii) an opinion, dated such Closing Date, of Cahill Gordon & Reindel LLP, counsel for Saratoga Partners III, L.P. and Saratoga Partners III, CV, in the form attached hereto as Exhibit D-1; and (iii) an opinion, dated such Closing Date, of [ ], counsel for Brown University Third Century Fund, in the form attached hereto as Exhibit D-2.

(g) The Representatives shall have received from Cravath, Swaine & Moore LLP, counsel for the Underwriters, such opinion or opinions, dated such Closing Date, with respect to such matters as the Representatives may require, and the Selling Shareholders and the Company shall have furnished to such counsel such documents as they request for the purpose of enabling them to pass upon such matters.

(h) The Representatives shall have received a certificate, dated such Closing Date, of the president or any vice president and a principal financial or accounting officer of the Company in which such officers shall state that to the best of their knowledge after reasonable investigation: the representations and warranties of the Company in this Agreement are true and correct in all material respects; the Company has in all material respects complied with all agreements and satisfied all conditions on its part to be performed or satisfied hereunder at or prior to such Closing Date; no stop order suspending the effectiveness of any Registration Statement has been issued and no proceedings for that purpose have been instituted or are contemplated by the Commission; the Additional Registration Statement (if any) satisfying the requirements of subparagraphs (1) and (3) of Rule 462(b) was filed pursuant to Rule 462(b), including payment of the applicable filing fee in accordance with Rule 111(a) or (b) under the Act, prior to the Applicable Time; and, subsequent to the respective date of the most recent financial statements in the General Disclosure Package, there has been no material adverse change, or any development or event involving a prospective material adverse change, in the condition (financial or other), business, properties or results of operations of the Company and its subsidiaries taken as a whole, except as set forth in the General Disclosure Package or as described in such certificate.

(i) The Representatives shall have received a letter, dated such Closing Date, of Ernst & Young LLP which meets the requirements of subsection (a) of this Section, except that the specified date referred to in such subsection will be a date not more than three days prior to such Closing Date for the purposes of this subsection.

(j) On or prior to the date of this Agreement, the Representatives shall have received lock-up letters, each substantially in the form of Exhibit E hereto, from each person listed on Schedule E.

(k) The Custodian will deliver to CSS a letter stating that they will deliver to each Selling Shareholder on or before January 31 of the year following the date of this Agreement, a United States Treasury Department Form 1099 (or other applicable form or statement specified by the United States Treasury Department regulations in lieu thereof).

The Selling Shareholders and the Company will furnish the Representatives with such conformed copies of such opinions, certificates, letters and documents as the Representatives reasonably request. CSS may in its sole discretion waive on behalf of the Underwriters compliance with any conditions to the obligations of the Underwriters hereunder, whether in respect of an Optional Closing Date or otherwise.

8. Indemnification and Contribution. (a) The Company will indemnify and hold harmless each Underwriter, its partners, members, directors, officers and its affiliates and each person, if any who controls such Underwriter within the meaning of Section 15 of the Act, against any losses, claims, damages or liabilities, joint or several, to which such Underwriter may become subject, under the Act or otherwise, insofar as such losses, claims, damages or liabilities (or actions in respect thereof) arise out of or are based upon any untrue statement or alleged untrue statement of any material fact contained in any Registration Statement, each Statutory Prospectus, the Prospectus, any Issuer Free Writing Prospectus, or any amendment or supplement thereto, or any related preliminary prospectus, or arise out of or are based upon the omission or alleged omission to state therein a material fact required to be stated therein and in the case of the Prospectus, in light of the circumstances under which they were made, or necessary to make the statements therein not misleading, and will reimburse each Underwriter for any legal or other expenses reasonably incurred by such Underwriter in connection with investigating or defending any such loss, claim, damage, liability or action as such expenses are incurred; provided, however, that the Company 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 an untrue statement or alleged untrue statement in or omission or alleged omission from any of such documents in reliance upon and in conformity with written information furnished to the Company by any Underwriter through the Representatives specifically for use therein, it being understood and agreed that the only such information furnished by any Underwriter consists of the information described as such in subsection (c) below.

The Company agrees to indemnify and hold harmless the Designated Underwriter and each person, if any, who controls the Designated Underwriter within the meaning of either Section 15 of the Securities Act or Section 20 of the Exchange Act (the “Designated Entities”), from and against any and all losses, claims, damages and liabilities (including, without limitation, any legal or other expenses reasonably incurred in connection with defending or investigating any such action or claim) (i) caused by any untrue statement or alleged untrue statement of a material fact contained in any material prepared by or with the consent of the Company for distribution to Participants in connection with the Directed Share Program or caused by any omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading; (ii) caused by the failure of any Participant to pay for and accept delivery of Directed Shares that the Participant agreed to purchase; or (iii) related to, arising out of, or in connection with the Directed Share Program, other than losses, claims, damages or liabilities (or expenses relating thereto) that are finally judicially determined to have resulted from the bad faith or gross negligence of the Designated Entities.

(b) Each Selling Shareholder, severally and not jointly, will indemnify and hold harmless each Underwriter, its partners, members, directors, officers and its affiliates and each person who controls such Underwriter within the meaning of Section 15 of the Act, against any losses, claims, damages or liabilities, joint or several, to which such Underwriter may become subject, under the Act or otherwise, insofar as such losses, claims, damages or liabilities (or actions in respect thereof) arise out of or are based upon any untrue statement or alleged untrue statement of any material fact contained in any Registration Statement, each Statutory Prospectus, the Prospectus, any Issuer Free Writing Prospectus, or any amendment or supplement thereto, or any related preliminary prospectus, 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 and in the case of the Prospectus, in light of the circumstances under which they were made, not misleading in each case to the extent, but only to the extent, that such untrue statement or omission or alleged omission was made in reliance upon and in conformity with written information furnished to the Company by such Selling Shareholder specifically for use therein, and will reimburse each Underwriter for any legal or other expenses reasonably incurred by such Underwriter in connection with investigating or defending any such loss, claim, damage, liability or action as such expenses are incurred.

(c) Each Underwriter will severally and not jointly indemnify and hold harmless the Company, its directors and officers and each person, if any, who controls the Company within the meaning of Section 15 of the Act, and each Selling Shareholder against any losses, claims, damages or liabilities to which the Company or such Selling Shareholder may become subject, under the Act or otherwise, insofar as such losses, claims, damages or liabilities (or actions in respect thereof) arise out of or are based upon any untrue statement or alleged untrue statement of any material fact contained in any Registration Statement, the Prospectus, or any amendment or supplement thereto, or any related preliminary prospectus, or arise out of or are based upon the omission or the alleged omission to state therein a material fact required to be stated therein or necessary in order to make the statements therein and in the case of the Prospectus, in light of the circumstances under which they were made, not misleading, in each case to the extent, but only to the extent, that such untrue statement or alleged untrue statement or omission or alleged omission was made in reliance upon and in conformity with written information furnished to the Company by such Underwriter through the Representatives specifically for use therein, and will reimburse any legal or other expenses reasonably incurred by the Company and such Selling Shareholder in connection with investigating or defending any such loss, claim, damage, liability or action as such expenses are incurred, it being understood and agreed that the only such information furnished by any Underwriter consists of the following information in the Prospectus furnished on behalf of each Underwriter: the fourth, sixth and fourteenth paragraphs under the caption “Underwriting”.

(d) Promptly after receipt by an indemnified party under this Section of notice of the commencement of any action, such indemnified party will, if a claim in respect thereof is to be made against an indemnifying party under subsection (a), (b) or (c) above, notify the indemnifying party of the commencement thereof; but the failure to notify the indemnifying party shall not relieve it from any liability that it may have under subsection (a), (b) or (c) above except to the extent that it has been materially prejudiced (through the forfeiture of substantive rights or defenses) by such failure; and provided further that the failure to notify the indemnifying party shall not relieve it from any liability that it may have to an indemnified party otherwise than under subsection (a), (b) or (c) above. In case any such action is brought against any indemnified party and it notifies an indemnifying party of the commencement thereof, the indemnifying party will be entitled to participate therein and, to the extent that it may wish, jointly with any other indemnifying party similarly notified, to assume the defense thereof, with counsel satisfactory to such indemnified party (who shall not, except with the consent of the indemnified party, be counsel to the indemnifying party), and after notice from the indemnifying party to such indemnified party of its election so to assume the defense thereof, the indemnifying party will not be liable to such indemnified party under this Section for any legal or other expenses subsequently incurred by such indemnified party in connection with the defense thereof other than reasonable costs of investigation. Notwithstanding anything contained herein to the contrary, if indemnity may be sought pursuant to the last paragraph in Section 8(a) hereof in respect of such action or proceeding, then in addition to such separate firm for the indemnified parties, the indemnifying party shall be liable for the reasonable fees and expenses of not more than one separate firm (in addition to any local counsel) for the Designated Underwriter for the defense of any losses, claims, damages and liabilities arising out of the Directed Share Program, and all persons, if any, who control the Designated Underwriter within the meaning of either Section 15 of the Act of Section 20 of the Exchange Act. No indemnifying party shall, without the prior written consent of the indemnified party, effect any settlement of any pending or threatened action in respect of which any indemnified party is or could have been a party and indemnity could have been sought hereunder by such indemnified party unless such settlement (i) includes an unconditional release of such indemnified party from all liability on any claims that are the subject matter of such action 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 an indemnified party. No indemnifying party shall be liable for any settlement or compromise of, or consent to the entry of judgment with respect to, any action or claim effected without its consent; provided, however, that if at any time an indemnified party shall have requested an indemnifying party to reimburse the indemnified party for fees and expenses of counsel in accordance with the provisions hereof, such indemnifying party agrees that it shall be liable for any settlement of the nature contemplated by Section 8(a) effected without its written consent if (i) such settlement is entered into in good faith by the indemnified party more than 45 days after receipt by such indemnifying party of the aforesaid request, (ii) such indemnifying party shall have received notice of the terms of such settlement at least 30 days prior to such settlement being entered into and (iii) such indemnifying party shall not have reimbursed such indemnified party in accordance with such request prior to the date of such settlement.

(e) If the indemnification provided for in this Section is unavailable or insufficient to hold harmless an indemnified party under subsection (a), (b) or (c) above, then each indemnifying party shall contribute to the amount paid or payable by such indemnified party as a result of the losses, claims, damages or liabilities referred to in subsection (a), (b) or (c) above: (i) in such proportion as is appropriate to reflect the relative benefits received by the

Company and the Selling Shareholders on the one hand and the Underwriters on the other from the offering of the Offered Securities or (ii) if the allocation provided by clause (i) above is not permitted by applicable law, in such proportion as is appropriate to reflect not only the relative benefits referred to in clause (i) above but also the relative fault of the Company and the Selling Shareholders on the one hand and the Underwriters on the other in connection with the statements or omissions which resulted in such losses, claims, damages or liabilities as well as any other relevant equitable considerations. The relative benefits received by the Company and the Selling Shareholders on the one hand and the Underwriters on the other shall be deemed to be in the same proportion as the total net proceeds from the offering (before deducting expenses) received by the Company and the Selling Shareholders bear to the total underwriting discounts and commissions received by the Underwriters under this Agreement. The relative fault shall be determined by reference to, among other things, whether the untrue or alleged untrue statement of a material fact or the omission or alleged omission to state a material fact relates to information supplied by the Company, the Selling Shareholders or the Underwriters and the parties’ relative intent, knowledge, access to information and opportunity to correct or prevent such untrue statement or omission. The amount paid by an indemnified party as a result of the losses, claims, damages or liabilities referred to in the first sentence of this subsection (e) shall be deemed to include any legal or other expenses reasonably incurred by such indemnified party in connection with investigating or defending any action or claim which is the subject of this subsection (e). Notwithstanding the provisions of this subsection (e), (A) no Underwriter shall be required to contribute any amount in excess of the amount by which the total price at which the Securities underwritten by it and distributed to the public were offered to the public exceeds the amount of any damages which such Underwriter has otherwise been required to pay by reason of such untrue or alleged untrue statement or omission or alleged omission and (B) each Selling Shareholder shall not be required to contribute any amount in excess of the amount by which the aggregate gross proceeds to such Selling Shareholder from the sale of Offered Securities by such Selling Shareholder hereunder, after deducting underwriting discounts and commissions but before out-of-pocket expenses, if any, exceeds the amount of any damages that such Selling Shareholder has otherwise been required to pay by reason of such untrue or alleged untrue statement or omission or alleged omission. 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. The Underwriters’ obligations in this subsection (e) to contribute are several in proportion to their respective underwriting obligations and not joint.

(f) The obligations of the Company and the Selling Shareholders under this Section shall be in addition to any liability which the Company and the Selling Shareholders may otherwise have and shall extend, upon the same terms and conditions, to each person, if any, who controls any Underwriter (as hereinafter defined) within the meaning of the Act; and the obligations of the Underwriters under this Section shall be in addition to any liability which the respective Underwriters may otherwise have and shall extend, upon the same terms and conditions, to each director of the Company, to each officer of the Company who has signed a Registration Statement and to each person, if any, who controls the Company within the meaning of the Act.

9. Default of Underwriters. If any Underwriter or Underwriters default in their obligations to purchase Offered Securities hereunder on either the First or any Optional Closing Date and the aggregate number of shares of Offered Securities that such defaulting Underwriter or Underwriters agreed but failed to purchase does not exceed 10% of the total number of shares of Offered Securities that the Underwriters are obligated to purchase on such Closing Date, CSS may make arrangements satisfactory to the Company and the Selling Shareholders for the purchase of such Offered Securities by other persons, including any of the Underwriters, but if no such arrangements are made by such Closing Date, the non-defaulting Underwriters shall be obligated severally, in proportion to their respective commitments hereunder, to purchase the Offered Securities that such defaulting Underwriters agreed but failed to purchase on such Closing Date. If any Underwriter or Underwriters so default and the aggregate number of shares of Offered Securities with respect to which such default or defaults occur exceeds 10% of the total number of shares of Offered Securities that the Underwriters are obligated to purchase on such Closing Date and arrangements satisfactory to CSS, the Company and the Selling Shareholders for the purchase of such Offered Securities by other persons are not made within 36 hours after such default, this Agreement will terminate without liability on the part of any non-defaulting Underwriter, the Company or the Selling Shareholders, except as provided in Section 10 (provided that if such default occurs with respect to Optional Securities after the First Closing Date, this Agreement will not terminate as to the Firm Securities or any Optional Securities purchased prior to such termination). As used in this Agreement, the term “Underwriter” includes any person substituted for an Underwriter under this Section. Nothing herein will relieve a defaulting Underwriter from liability for its default.

10. Survival of Certain Representations and Obligations. The respective indemnities, agreements, representations, warranties and other statements of the Selling Shareholders, of the Company or its officers and of

the several Underwriters set forth in or made pursuant to this Agreement will remain in full force and effect, regardless of any investigation, or statement as to the results thereof, made by or on behalf of any Underwriter, Selling Shareholder, the Company or any of their respective representatives, officers or directors or any controlling person, and will survive delivery of and payment for the Offered Securities. If this Agreement is terminated pursuant to Section 9 or if for any reason the purchase of the Offered Securities by the Underwriters is not consummated, the Company and the Selling Shareholders shall remain responsible for the expenses to be paid or reimbursed by them pursuant to Section 5 and the respective obligations of the Company, the Selling Shareholders, and the Underwriters pursuant to Section 8 shall remain in effect, and if any Offered Securities have been purchased hereunder the representations and warranties in Section 2 and all obligations under Section 5 shall also remain in effect. If the purchase of the Offered Securities by the Underwriters is not consummated for any reason other than solely because of the termination of this Agreement pursuant to Section 9 or the occurrence of any event specified in clause (iii), (iv), (vi), (vii) or (viii) of Section 7(c), the Company will reimburse the Underwriters for all reasonable out-of-pocket expenses (including reasonable fees and disbursements of counsel) reasonably incurred by them in connection with the offering of the Offered Securities.

11. Notices. All communications hereunder will be in writing and, if sent to the Underwriters, will be mailed, delivered or telegraphed and confirmed to the Representatives, c/o Credit Suisse Securities (USA) LLC, Eleven Madison Avenue, New York, N.Y. 10010-3629, Attention: Transactions Advisory Group, or, if sent to the Company, will be mailed, delivered or telegraphed and confirmed to it at 436 Seventh Avenue, Pittsburgh, PA 15219, Attention: Steven R. Lacy, Esq., or, if sent to the Selling Shareholders or any of them, will be mailed, delivered or telegraphed and confirmed to Steven R. Lacy, Esq., c/o the Company; provided, however, that any notice to an Underwriter pursuant to Section 8 will be mailed, delivered or telegraphed and confirmed to such Underwriter.

12. Successors. This Agreement will inure to the benefit of and be binding upon the parties hereto and their respective personal representatives and successors and the officers and directors and controlling persons referred to in Section 7, and no other person will have any right or obligation hereunder.

13. Representation. The Representatives will act for the several Underwriters in connection with the transactions contemplated by this Agreement, and any action under this Agreement taken by the Representatives jointly or by CSS will be binding upon all the Underwriters. [ ] will act for the Selling Shareholders in connection with such transactions, and any action under or in respect of this Agreement taken by [ ] will be binding upon all the Selling Shareholders.

14. Counterparts. This Agreement may be executed in any number of counterparts, each of which shall be deemed to be an original, but all such counterparts shall together constitute one and the same Agreement.

15. Absence of Fiduciary Relationship. The Company and the Selling Shareholders acknowledge and agree that:

(a) the Representatives have been retained solely to act as underwriters in connection with the sale of the Company’s securities and that no fiduciary, advisory or agency relationship between the Company or the Selling Shareholders, on the one hand, and the Representatives, on the other, has been created in respect of any of the transactions contemplated by this Agreement, irrespective of whether the Representatives have advised or is advising the Company or the Selling Shareholders on other matters;

(b) the price of the securities set forth in this Agreement was established by the Company and the Selling Shareholders following discussions and arm’s-length negotiations with the Representatives and the Company and the Selling Shareholders are capable of evaluating and understanding and understand and accept the terms, risks and conditions of the transactions contemplated by this Agreement;

(c) it and the Selling Shareholders have been advised that the Representatives and their affiliates are engaged in a broad range of transactions which may involve interests that differ from those of the Company or the Selling Shareholders and that the Representatives have no obligation to disclose such interests and transactions to the Company or the Selling Shareholders by virtue of any fiduciary, advisory or agency relationship; and

(d) it and the Selling Shareholders waive, to the fullest extent permitted by law, any claims they may have against the Representatives for breach of fiduciary duty or alleged breach of fiduciary duty and agree that the

Representatives shall have no liability (whether direct or indirect) to the Company or the Selling Shareholders in respect of such a fiduciary duty claim or to any person asserting a fiduciary duty claim on behalf of or in right of the Company, including Shareholders, employees or creditors of the Company.

16. Applicable Law. This Agreement shall be governed by, and construed in accordance with, the laws of the State of New York, without regard to principles of conflicts of laws.

The Company hereby submits to the exclusive jurisdiction of the Federal and state courts in the Borough of Manhattan in The City of New York in any suit or proceeding arising out of or relating to this Agreement or the transactions contemplated hereby. Each underwriter, the Selling Shareholders and the Company (on its behalf and, to the extent permitted by applicable law, on behalf of its shareholders and affiliates) waives 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 Remainder of This Page Intentionally Left Blank; Signature Page Follows]

If the foregoing is in accordance with the Representatives’ understanding of our agreement, kindly sign and return to the Company one of the counterparts hereof, whereupon it will become a binding agreement among the Selling Shareholders, the Company and the several Underwriters in accordance with its terms.


Very truly yours,

KOPPERS HOLDINGS INC.

By:
Name:
Title:

The Selling Shareholders named in
Schedule B attached thereto

By:
Name:
Title:		Attorney In Fact

As an inducement to the underwriters to execute an underwriting agreement (the “Underwriting Agreement”), pursuant to which an offering will be made that is intended to result in the establishment of a public market for the Common Stock, par value $0.01 per share (the “Securities”), of Koppers Holdings Inc., and any successor (by merger or otherwise) thereto (the “Company”), the undersigned hereby agrees that during the period specified in the following paragraph (the “Lock-Up Period”), the undersigned will not offer, sell, contract to sell, pledge or otherwise dispose of, directly or indirectly, any Securities or securities convertible into or exchangeable or exercisable for Securities, enter into a transaction which would have the same effect, or enter into any swap, hedge or other arrangement that transfers, in whole or in part, any of the economic consequences of ownership of Securities, whether any such aforementioned transaction is to be settled by delivery of Securities or such other securities, in cash or otherwise, or publicly disclose the intention to make any such offer, sale, pledge or disposition, or to enter into any such transaction, swap, hedge or other arrangement, without, in each case, the prior written consent of Credit Suisse Securities (USA) LLC (“CSS”) and UBS Securities LLC (“UBS”). In addition, the undersigned agrees that, without the prior written consent of CSS and UBS, it will not, during the Lock-Up Period, make any demand for or exercise any right with respect to, the registration of any Securities or any security convertible into or exercisable or exchangeable for the Securities.

The initial Lock-Up Period will commence on the date of this Lock-Up Agreement and continue and include the date 180 days after the public offering date set forth on the final prospectus used to sell the Securities (the “Public Offering Date”) pursuant to the Underwriting Agreement; provided, however, that if (1) during the last 17 days of the initial Lock-Up Period, the Company releases earnings results or material news or a material event relating to the Company occurs or (2) prior to the expiration of the initial Lock-Up Period, the Company announces that it will release earnings results during the 16-day period beginning on the last day of the initial Lock-Up Period, then in each case the Lock-Up Period will be extended until the expiration of the 18-day period beginning on the date of release of the earnings results or the occurrence of the material news or material event, as applicable, unless CSS and UBS waive, in writing, such extension.

The undersigned hereby acknowledges and agrees that written notice of any extension of the Lock-Up Period pursuant to the previous paragraph will be delivered by CSS and UBS to the Company (in accordance with Section 11 of the Underwriting Agreement) and that any such notice properly delivered will be deemed to have been given to, and received by, the undersigned. The undersigned further agrees that, prior to engaging in any transaction or taking any other action that is subject to the terms of this Lock-Up Agreement during the period from the date of this Lock-Up Agreement to and including the 34th day following the expiration of the initial Lock-Up Period, it will give notice thereof to the Company and will not consummate such transaction or take any such action unless it has received written confirmation from the Company that the Lock-Up Period (as may have been extended pursuant to the previous paragraph) has expired.

The restrictions set forth herein shall not apply to (1) the sale of any stock to the underwriters pursuant to the Underwriting Agreement; (2) sales or transfers of stock acquired in open market

transactions; and (3) the conversion of any options into stock, as contemplated in the prospectus in connection with the offering. It shall be understood that such restrictions shall apply to the underlying stock received upon any such conversion.

Notwithstanding the foregoing, the undersigned may transfer any Security (i) as a bona fide gift or gifts, provided that the donee or donees thereof agree to be bound in writing by the restrictions set forth herein, (ii) to any trust for the direct or indirect benefit of the undersigned or the immediate family of the undersigned, provided that the trustee of the trust agrees to be bound in writing by the restrictions set forth herein, and provided further that any such transfer shall not involve a disposition for value or (iii) to the undersigned’s executors, administrators, testamentary trustees, legatees or beneficiaries upon the death of the undersigned. For purposes of this Agreement, “immediate family” shall mean any relationship by blood, marriage or adoption, not more remote than first cousin. In addition, notwithstanding the foregoing, if the undersigned is a partnership, corporation or limited liability company, such entity may transfer its Securities (a) to any general or limited partner, wholly-owned subsidiary, affiliate or member of such entity, (b) in connection with a statutory merger or consolidation of such entity or (c) to any of its shareholders, and such transferee may transfer Securities to any other shareholder, partner or member of the undersigned; provided , however, that (w) in any such case, it shall be a condition to the transfer that the transferee execute an agreement stating that the transferee is receiving and holding such Securities subject to the provisions of this Agreement and there shall be no further transfer of such Securities except in accordance with this Agreement, (x) any such transfer shall not involve a disposition for value, (y) no such transfer shall be effected on the New York Stock Exchange, the over-the-counter market or any other system providing share price quotations and (z) in the case of transfers pursuant to clauses (i), (ii) or (iii) no filing by any party (transferor or transferee) under the Securities Exchange Act of 1934, as amended, shall be required or voluntarily made in connection with such transfer.

In furtherance of the foregoing, the Company and its transfer agent and registrar are hereby authorized to decline to make any transfer of shares of Securities if such transfer would constitute a violation or breach of this Agreement.

This Agreement shall be binding on the undersigned and the successors and assigns of the undersigned. This Agreement shall lapse and become null and void if the Public Offering Date shall not have occurred on or before March 31, 2006.


Selling Shareholder	Number of Firm Securities To Be Sold	Number of Optional Securities To Be Sold
Saratoga Partners III, L.P.
Saratoga Partners III, CV
Brown University Third Century Fund

Total


Underwriter		Number of Firm Securities To Be Purchased
Credit Suisse Securities (USA) LLC
UBS Securities LLC
First Analysis Corporation
Jefferies & Company, Inc
Key Banc

Total