In enzymology, a trimethylamine dehydrogenase is an enzyme that catalyzes the chemical reaction The 3 substrates of this enzyme are trimethylamine, H2O, and electron-transferring flavoprotein, whereas its 3 products are dimethylamine, formaldehyde, and reduced electron-transferring flavoprotein. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH group of donors with a flavin as acceptor. The systematic name of this enzyme class is trimethylamine:electron-transferring flavoprotein oxidoreductase (demethylating). This enzyme participates in methane metabolism.