Indolin-2-one monooxygenase (, BX3 (gene), CYP71C2 (gene)) is an enzyme with systematic name indolin-2-one,NAD(P)H:oxygen oxidoreductase (3-hydroxylating). This enzyme catalyses the following chemical reaction
Indolin-2-one monooxygenase is involved in the biosynthesis of protective and allelopathic benzoxazinoids in some plants.