In enzymology, a hydrogenase (acceptor) () is an enzyme that catalyzes the chemical reaction
Thus, the two substrates of this enzyme are H<sub>2</sub> and A, whereas its product is AH<sub>2</sub>.
This enzyme belongs to the family of oxidoreductases, specifically those acting on hydrogen as donor with other acceptors. The systematic name of this enzyme class is hydrogen:acceptor oxidoreductase. Other names in common use include H2 producing hydrogenase[ambiguous], hydrogen-lyase[ambiguous], hydrogenlyase[ambiguous], uptake hydrogenase[ambiguous], and hydrogen:(acceptor) oxidoreductase.