A method of inhibiting scale formation by salts of calcium, magnesium, barium and strontium from aqueous solutions, by adding to the aqueous solution a minor proportion of a product comprising a telomer of formula I: ##STR1## or a salt thereof, wherein X is CO.sub.2 H when Y is H and vice versa, B and B' are each hydrogen or B is CH.sub.3 when B' is H or vice versa, m is an integer from 2 to 100 and n is 0 or 1, R is alkyl having 1 to 22 carbon atoms substituted by one or more hydroxy groups.