Exhibit 3.1

CERTIFICATE OF AMENDMENT

TO THE AMENDED AND RESTATED CERTIFICATE OF INCORPORATION

OF

HUMANIGEN, INC.

a Delaware corporation

Pursuant to Section 242 of the General Corporation Law of the State of Delaware (the “DGCL”), Humanigen, Inc., a corporation organized and existing under the DGCL (the “Corporation”), hereby certifies as follows:

A. On July 27, 2020, the Board of Directors of the Corporation duly adopted a resolution proposing and declaring advisable the following amendment (the “Amendment”) to the Corporation’s Amended and Restated Certificate of Incorporation, as amended (the “Certificate”).

B. Article IV of the Certificate is hereby amended by adding the following new paragraph to effectuate the Reverse Stock Split (as defined below):

“C. Reverse Stock Split. At 4:30 p.m. Eastern Time on September 11, 2020 (the “Effective Time”), pursuant to the Delaware General Corporation Law of this Certificate of Amendment to the Amended and Restated Certificate of Incorporation, as amended, of the Corporation, each five (5) shares of Common Stock issued and outstanding immediately prior to the Effective Time shall, automatically and without any action on the part of the respective holders thereof, be combined and converted into one (1) share of Common Stock (the “Reverse Stock Split”). No fractional shares shall be issued in connection with the Reverse Stock Split. Stockholders who otherwise would be entitled to receive fractional shares of Common Stock shall be entitled to receive cash (without interest or deduction) in lieu of such fractional share interests, in an amount equal to the proceeds attributable to the sale of such fractional shares following the aggregation and sale by the Corporation's transfer agent of all fractional shares otherwise issuable. Each certificate that immediately prior to the Effective Time represented shares of Common Stock (“Old Certificates”), shall thereafter represent that number of shares of Common Stock into which the shares of Common Stock represented by the Old Certificate shall have been combined, subject to the elimination of fractional share interests as described above.”

C. This Amendment to the Certificate has been duly approved and adopted by the written consent of a majority of the stockholders of the Corporation entitled to vote thereon in accordance with the provisions of Section 228 and Section 242 of the DGCL.

D. This Amendment to the Certificate shall be effective as of the Effective Time.

IN WITNESS WHEREOF, the Corporation has caused this Certificate of Amendment to the Amended and Restated Certificate of Incorporation, as amended, to be signed by a duly authorized officer of the Corporation on this 11th day of September, 2020.