In enzymology, L-lysine oxidase () is an enzyme that catalyzes the chemical reaction
The three substrates of this enzyme are L-lysine, water, and oxygen. Its products are 6-amino-2-oxohexanoic acid, hydrogen peroxide, and ammonia.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH<sub>2</sub> group of donors with oxygen as acceptor. The systematic name of this enzyme class is L-lysine:oxygen 2-oxidoreductase (deaminating). Other names in common use include L-lysine alpha-oxidase, and L-lysyl-alpha-oxidase. This enzyme participates in lysine degradation.