In enzymology, maleylacetate reductase () is an enzyme that catalyzes the chemical reaction
The two substrates of this enzyme are 3-oxoadipic acid, and oxidised nicotinamide adenine dinucleotide (NAD<sup>+</sup>). Its products are maleylacetic acid, reduced NADH, and a proton. The enzyme can use nicotinamide adenine dinucleotide phosphate as an alternative cofactor.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-CH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is 3-oxoadipate:NAD(P)+ oxidoreductase. This enzyme is also called maleolylacetate reductase. This enzyme participates in 3 metabolic pathways: gamma-hexachlorocyclohexane degradation, benzoate degradation via hydroxylation, and 1,4-dichlorobenzene degradation.