NATURAL GAS SERVICES GROUP, INC.

                                                                    EXHIBIT 99.2



                            CERTIFICATION PURSUANT TO
                               18 U.S.C. ss.1350,
                             AS ADOPTED PURSUANT TO
                  SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002


     In connection with the Quarterly Report of Natural Gas Services Group, Inc.
(the "Company") on Form 10-QSB for the period ended September 30, 2002, as filed
with the Securities and Exchange  Commission on the date hereof (the  "Report"),
I, Earl R. Wait, Chief Financial Officer of the Company, certify, pursuant to 18
U.S.C.  ss.1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of
2002, that:

     1.   The Report fully  complies  with the  requirement  so Section 13(a) or
          15(d) of the Securities Exchange Act of 1934; and

     2.   The  information  contained  in the  Report  fairly  presents,  in all
          material respects,  the financial  condition and results of operations
          of the Company.



                                                      /s/ Earl R. Wait
                                                     -----------------------
                                                     Earl R. Wait
                                                     Chief Financial Officer

                                                     November 12, 2002