In enzymology, a L-glycol dehydrogenase (EC 1.1.1.185) is an enzyme that catalyzes the chemical reaction

an L-glycol + NAD(P)⁺ ${\displaystyle \rightleftharpoons }$ a 2-hydroxycarbonyl compound + NAD(P)H + H⁺

The 3 substrates of this enzyme are L-glycol, NAD⁺, and NADP⁺, whereas its 4 products are 2-hydroxycarbonyl compound, NADH, NADPH, 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 L-glycol:NAD(P)⁺ oxidoreductase. Other names in common use include glycol (nicotinamide adenine dinucleotide (phosphate)), dehydrogenase, L-(+)-glycol:NAD(P)⁺ oxidoreductase, and L-glycol:NAD(P)⁺ dehydrogenase.