In enzymology, a hyponitrite reductase is an enzyme that catalyzes the oxidation of hydroxylamine by the nicotinamide adenine dinucleotide cation (NAD<sup>+</sup>) into hyponitrous acid HON=NOH:
This systematic name of this enzyme class hydroxylamine:NAD+ oxidoreductase. It is also called NADH2:hyponitrite oxidoreductase.
This enzyme belongs to the family of oxidoreductases, specifically those acting on other nitrogenous compounds as donors with NAD+ or NADP+ as acceptor. It employs one cofactor, metal.