In enzymology, a mannitol dehydrogenase (EC 1.1.1.255) is an enzyme that catalyzes the chemical reaction In enzymology, a mannitol dehydrogenase (EC 1.1.1.255) is an enzyme that catalyzes the chemical reaction Thus, the two substrates of this enzyme are D-mannitol and NAD+, whereas its 3 products are D-mannose, NADH, and H+. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is mannitol:NAD+ 1-oxidoreductase. Other names in common use include MTD, and NAD+-dependent mannitol dehydrogenase.