EXHIBIT 31.1

CERTIFICATIONS

I, Stephen C. Taylor, certify that:

1.I have reviewed this Amendment No. 1 to the annual report on Form 10-K of Natural Gas Services Group, Inc.; and

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report.

/s/ Stephen C. Taylor

Stephen C. Taylor

Chief Executive Officer and President (Principal Executive Officer)

April 23, 2019