In enzymology, a galactitol 2-dehydrogenase (EC 1.1.1.16) is an enzyme that catalyzes the chemical reaction

galactitol + NAD⁺ ${\displaystyle \rightleftharpoons }$ D-tagatose + NADH + H⁺

Thus, the two substrates of this enzyme are galactitol and NAD⁺, whereas its 3 products are D-tagatose, 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 galactitol:NAD⁺ 2-oxidoreductase. This enzyme is also called dulcitol dehydrogenase. This enzyme participates in galactose metabolism.