In enzymology, a fatty-acid peroxidase (EC 1.11.1.3) is an enzyme that catalyzes the chemical reaction

palmitate + 2 H₂O₂ ${\displaystyle \rightleftharpoons }$ pentadecanal + CO₂ + 3 H₂O

Thus, the two substrates of this enzyme are palmitate and H₂O₂, whereas its 3 products are pentadecanal, CO₂, and H₂O.

This enzyme belongs to the family of oxidoreductases, specifically those acting on a peroxide as acceptor (peroxidases). The systematic name of this enzyme class is hexadecanoate:hydrogen-peroxide oxidoreductase. This enzyme is also called long chain fatty acid peroxidase.