This invention relates to new products of the general formula: ##STR1## wherein C.sub.n F.sub.2n.sub.+1 represents a straight or branched perfluorinated hydrocarbon chain in which n is a number between 1 and 20; a is an even number having the value 2 or 4; R represents a hydrogen atom or the methyl radical; Z represents an alkyl hydrocarbon radical containing from 1 to 8 carbon atoms, or the radical -- CH.sub.2 -- CHOHR, or a cycloalkyl hydrocarbon radical containing from 5 to 9 carbon atoms or an aryl hydrocarbon radical containing from 6 to 10 carbon atoms; R' represents an alkyl hydrocarbon radical containing from 1 to 9 carbon atoms; and X is an anion which can be a halide, a sulphate, or an alkyl sulphate. These products are useful as surface active agents.