Ammonia monooxygenase of Nitrosomonas europaea catalyzes the oxidation of alkanes (up to C(8)) to alcohols and alkenes (up to C(5)) to epoxides and alcohols in the presence of ammonium ions. Straight-chain, N-terminal alkynes (up to C(10)) all exhibited a time-dependent inhibition of ammonia oxidation without effects on hydrazine oxidation.