Peroxydisulfuric acid

Peroxydisulfuric  is a sulfur oxoacid with the chemical formula H2S2O8. In structural terms it can be written HO3SOOSO3H. It is one of a group of sulfur oxoacids, its salts, commonly known as persulfates, are industrially important but the acid itself is not. The salts contain the peroxydisulfate ion.