In enzymology, isoquinoline 1-oxidoreductase () is an enzyme that catalyzes the chemical reaction
The three substrates of this enzyme are isoquinoline, an electron acceptor, and water. Its products are isocarbostyril and reduced acceptor.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-CH group of donor with other acceptors. The systematic name of this enzyme class is isoquinoline:acceptor 1-oxidoreductase (hydroxylating).