In enzymology, a serine 2-dehydrogenase (EC 1.4.1.7) is an enzyme that catalyzes the chemical reaction

L-serine + H₂O + NAD⁺ ${\displaystyle \rightleftharpoons }$ 3-hydroxypyruvate + NH₃ + NADH + H⁺

The 3 substrates of this enzyme are L-serine, H₂O, and NAD⁺, whereas its 4 products are 3-hydroxypyruvate, NH₃, NADH, and H⁺.

This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH2 group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is L-serine:NAD+ 2-oxidoreductase (deaminating). Other names in common use include L-serine:NAD+ oxidoreductase (deaminating), and serine dehydrogenase.