In enzymology, an inositol 2-dehydrogenase () is an enzyme that catalyzes the chemical reaction
The two substrates of this enzyme are myo-inositol and oxidised nicotinamide adenine dinucleotide (NAD<sup>+</sup>). Its products are 2,4,6/3,5-pentahydroxycyclohexanone, reduced NADH, and a proton.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD<sup>+</sup> or NADP<sup>+</sup> as acceptor. The systematic name of this enzyme class is myo-inositol:NAD<sup>+</sup> 2-oxidoreductase. Other names in common use include myo-inositol 2-dehydrogenase, myo-inositol:NAD<sup>+</sup> oxidoreductase, inositol dehydrogenase, and myo-inositol dehydrogenase. This enzyme participates in inositol metabolism and inositol phosphate metabolism.