Chloridazon-catechol dioxygenase () is an enzyme that catalyzes the chemical reaction
Thus, the two substrates of this enzyme are 5-amino-4-chloro-2-(2,3-dihydroxyphenyl)-3(2H)-pyridazinone and oxygen, whereas its product is 5-amino-4-chloro-2-(2-hydroxymuconoyl)-3(2H)-pyridazinone.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O<sub>2</sub> as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O<sub>2</sub>. The systematic name of this enzyme class is 5-amino-4-chloro-2-(2,3-dihydroxyphenyl)-3(2H)-pyridazinone 1,2-oxidoreductase (decyclizing). It employs one cofactor, iron.