In enzymology, a trimethylamine-N-oxide reductase (cytochrome c) () is an enzyme that catalyzes the chemical reaction
The 3 substrates of this enzyme are trimethylamine, (ferricytochrome c)-subunit, and H<sub>2</sub>O, whereas its 3 products are trimethylamine N-oxide, (ferrocytochrome c)-subunit, and H<sup>+</sup>.
This enzyme belongs to the family of oxidoreductases, specifically those acting on other nitrogenous compounds as donors with a cytochrome as acceptor. The systematic name of this enzyme class is trimethylamine:cytochrome c oxidoreductase. Other names in common use include TMAO reductase, and TOR. This enzyme participates in two-component system - general.