Trifluoromethanesulfonic anhydride, also known as triflic anhydride, is the chemical compound with the formula (CFSO)O. It is the acid anhydride derived from triflic acid. This compound is a strong electrophile, useful for introducing the triflyl group, CFSO. Abbreviated TfO, triflic anhydride is the acid anhydride of the superacid triflic acid, CFSOOH.