In enzymology, a 1-hydroxy-2-naphthoate 1,2-dioxygenase (EC 1.13.11.38) is an enzyme that catalyzes the chemical reaction

1-hydroxy-2-naphthoate + O₂ ${\displaystyle \rightleftharpoons }$ (3Z)-4-(2-carboxyphenyl)-2-oxobut-3-enoate

Thus, the two substrates of this enzyme are 1-hydroxy-2-naphthoate and O₂, whereas its product is (3Z)-4-(2-carboxyphenyl)-2-oxobut-3-enoate.

This enzyme participates in naphthalene and anthracene degradation. It employs one cofactor, iron.

This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O₂ as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O₂. The systematic name of this enzyme class is 1-hydroxy-2-naphthoate:oxygen 1,2-oxidoreductase (decyclizing). Other names in common use include 1-hydroxy-2-naphthoate dioxygenase, 1-hydroxy-2-naphthoate-degrading enzyme, and 1-hydroxy-2-naphthoic acid dioxygenase.