Chlorite dismutase, also known as Chlorite O2-lyase (EC ), is an enzyme that catalyzes the chemical reaction

ClO−2 → Cl− + O2

Reactions that generate oxygen molecules are exceedingly rare in biology, except in photosynthesis, and they are difficult to mimic synthetically. Perchlorate-respiring bacteria enzymatically detoxify chlorite (ClO−2), the end product of the perchlorate (ClO−4) respiratory pathway, by converting it to dioxygen (O2) and chloride (Cl−). Chlorite dismutase is a hemoprotein, but it bears no structural or sequence relationships with known peroxidases or other heme proteins, and is part of a large family of proteins with more than one biochemical function.