In enzymology, a thiamine oxidase () is an enzyme that catalyzes the chemical reaction thiamine + 2 O2 + H2O thiamine acetic acid + 2 H2O2 The 3 substrates of this enzyme are thiamine, O2, and H2O, whereas its two products are thiamine acetic acid and H2O2. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with oxygen as acceptor. The systematic name of this enzyme class is thiamine:oxygen 5-oxidoreductase. Other names in common use include thiamin dehydrogenase, thiamine dehydrogenase, and thiamin:oxygen 5-oxidoreductase. This enzyme participates in thiamine metabolism. It employs one cofactor, FAD. References EC 1.1.3 Flavoproteins Enzymes of unknown structure