Disclosed are alkali and ammonium polyoxapolyfluoroalkanesulphonates having the formula:A-[CF.sub.2 O--(C.sub.2 F.sub.4 O).sub.m (CF.sub.2 O).sub.n --CF.sub.2 ]-Band the free acids thereof, in which the oxyperfluoroalkylene units --C.sub.2 F.sub.4 O--and --CF.sub.2 O-- are randomly distributed along the chain; m and n are integers the sum of which is a number from 2 to 50, and preferably from 4 to 20; the m/n ratio is between 0.2 and 1.5; A is a monovalent radical --CH.sub.2 O--R--SO.sub.3 M, wherein R is a divalent radical in alpha-gamma or alpha-delta position and is selected from the group consisting of alkylene, cycloalkylene, arylene and benzylene radicals, optionally containing, as substituents, chlorine atoms or alkylene or alkoxy groups; and M is an alkali metal, hydrogen or an ammonium group; and B is the same as A or is the radical --CH.sub.2 OH. These products are prepared by reacting .alpha.,.omega.-bis(hydroxymethyl)polyoxaperfluoroalkanes having the formulaHO-CH.sub.2 -[CF.sub.2 O-(C.sub.2 F.sub.4 O).sub.m (CF.sub.2 O).sub.n -CF.sub.2 ]-CH.sub.2 OH,or the alkali or ammonium dialcoholates thereof, with a sultone of the formula ##STR1## wherein R is a divalent radical in alpha-gamma or alpha-delta position and is selected from the group consisting of alkylene, cycloalkylene, arylene and benzylene radicals.