Exhibit 31.2

CERTIFICATION PURSUANT TO

RULE 13a-14(a) and 15d-14(a) UNDER THE SECURITIES EXCHANGE ACT OF 1934,

AS AMENDED

I, Mark R. Harris, Chief Financial Officer, certify that:

1. I have reviewed this Amendment No. 1 on Form 10-K/A to the Annual Report on Form 10-K of Hercules Capital, Inc. (the “registrant”) for the year ended December 31, 2016; 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.