In chemistry, peroxycarbonate (sometimes peroxocarbonate, IUPAC name: oxocarbonate or oxidocarbonate) or percarbonate is a divalent anion with formula . It is an oxocarbon anion that consists solely of carbon and oxygen. It would be the anion of a hypothetical peroxycarbonic acid HO–CO–O–OH (sometimes peroxocarbonic acid). or the real hydroperoxyformic acid, HO-O-CO-OH (a.k.a. percarbonic acid, carbonoperoxoic acid, hydroxycarbonic acid).
The peroxycarbonate anion is formed, together with peroxydicarbonate , at the negative electrode during electrolysis of molten lithium carbonate. Lithium peroxycarbonate can be produced also by combining carbon dioxide  with lithium hydroxide in concentrated hydrogen peroxide HO at −10 °C.
Electrolysis of a solution of lithium carbonate at -30° to -40 °C yields a solution of the Lithium percarbonate, which can liberate iodine from potassium iodide instantaneously. The crystalline salt has not been isolated.
The peroxycarbonate anion has been proposed as an intermediate to explain the catalytic effect of CO on the oxidation of organic compounds by O.
The potassium and rubidium salts of the monovalent hydrogenperoxycarbonate anion (aka. hydroxycarbonate, biperoxycarbonate)  have also been obtained.