NGSG VOTE BY INTERNET – www.proxyvote.com

NATURAL GAS SERVICES GROUP, INC. Use the Internet to transmit your voting instructions and for electronic delivery, of information, up until 11:59 P.M. Eastern Time, June 14, 2017.

NATURAL GAS SERVICES GROUP, INC

508 WEST WALL STREET, SUITE 550 Have your proxy card in hand when you access the web site and

MIDLAND, TX 79701 follow the instructions to obtain your records and to create an electronic

voting instruction form.

VOTE BY PHONE – 1-800-690-6903

Use any touch-tone telephone to transmit your voting instructions and for electronic delivery, of information, up until 11:59 P.M. Eastern Time, June 15, 2017. Have your proxy card in hand when you call and then follow the instructions.

VOTE BY MAIL

Mark, sign and date your proxy card and return it in the postage-paid envelope we have provided or return it to Vote Processing, c/o Broadridge, 51 Mercedes Way, Edgewood, NY 11717.

TO VOTE, MARK BLOCKS BELOW IN BLUE OR BLACK INK AS FOLLOWS: KEEP THIS PORTION FOR YOUR RECORDS

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

DETACH AND RETURN THIS PORTION ONLY

THIS PROXY CARD IS VALIDED AND DATED.

Important Notice Regarding the Availability of Proxy Materials for the Annual Meeting: The Notice & Proxy Statement, 10-K/Annual Report Combo is/are available at www.proxyvote.com .

— — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — —

NATURAL GAS SERVICES GROUP, INC.

THIS PROXY IS SOLICITED ON BEHALF OF THE BOARD OF DIRECTORS

ANNUAL MEETING OF SHAREHOLDERS JUNE 15, 2017.

The shareholder(s) hereby appoint(s) Stephen C. Taylor and G. Larry Lawrence, or either of them, as proxies, each with the power to appoint his substitute, and hereby authorizes them to represent and to vote, as designated on the reverse side of this ballot, all of the shares of Common Stock of NATURAL GAS SERVICES GROUP, INC. that the shareholder(s) is/are entitled to vote at the Annual Meeting of Shareholders to be held at 8:30 AM, CDT on June 15, 2017, at the Petroleum Club of Midland, at 501 West Wall Street, Midland, TX 79701, and any adjournment or postponement thereof.

THIS PROXY, WHEN PROPERLY EXECUTED WILL BE VOTED AS DIRECTED BY THE SHAREHOLDER(S). IF NO SUCH DIRECTIONS ARE MADE, THIS PROXY WILL BE VOTED FOR THE ELECTION OF THE NOMINEE LISTED ON THE REVERSE SIDE FOR THE BOARD OF DIRECTORS, FOR ITEMS 2, AND 4, AND"ONE YEAR" FOR ITEM 3. IF ANY OTHER MATTER PROPERLY COMES BEFORE THE MEETING, THE PERSONS NAMED IN THE PROXY WILL VOTE IN THEIR DISCRETION.

PLEASE MARK, SIGN, DATE AND RETURN THIS PROXY CARD PROMPTLY USING THE ENCLOSED REPLY ENVELOPE.

Continued and to be signed on reverse side