In enzymology, an aryl-aldehyde dehydrogenase (EC 1.2.1.29) is an enzyme that catalyzes the chemical reaction

an aromatic aldehyde + NAD⁺ + H₂O ${\displaystyle \rightleftharpoons }$ an aromatic acid + NADH + H⁺

The 3 substrates of this enzyme are aromatic aldehyde, NAD⁺, and H₂O, whereas its 3 products are aromatic acid, NADH, and H⁺.

This enzyme belongs to the family of oxidoreductases, specifically those acting on the aldehyde or oxo group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is aryl-aldehyde:NAD+ oxidoreductase. This enzyme participates in tyrosine metabolism and biphenyl degradation.