 Peroxide

A peroxide contains an oxygen-oxygen unit, formally ${\mathrm{O}}_2^{2-}$ in an ionic description or an O-O single bond in compounds such as hydrogen peroxide. The oxygen oxidation state differs from that in an ordinary oxide.

Cleavage or transfer involving the oxygen-oxygen bond contributes to characteristic redox and radical chemistry. A peroxide is therefore not defined merely by having two oxygen atoms anywhere in its formula.