CH2OPO(OH) (OM!) and potassium nonadecafiuorodecyl phosphate, F(CF2) 9CHzOPO(OH) (OK) There may also be used the di(fiuoroalkyl)- phosphates of the formula (B(CF2) nCHZO) 2PO(OM) where B is hydrogen or fluorine and n is an integer at least equal to 5, which are prepared in substantially the same manner as the mono- (fluoroalkyl) phosphates.