Fatty esters of oligoesters of a dicarboxylic acid and a polyol retaining at least one free hydroxyl group, particularly of the formula (I): R.sup.1--[OR.sup.2O--C(O)--R.sup.3--(O)C--].sub.m--R.sup.4 (I), where R.sup.1 is H, a monocarboxylic acid group, or R.sup.6O--[C(O)--R.sup.3--(O)C]--; R.sup.2s are residues of polyols having at least one substituent free hydroxyl; R.sup.3s are hydrocarbylene; R.sup.4 is --OH, --OM where M is a salt forming metal, amine or ammonium, --OR.sup.6, or --OR.sup.2O--R.sup.7; R.sup.5 is C.sub.7 to C.sub.21 hydrocarbyl; R.sup.6 is C.sub.8 to C.sub.22 hydrocarbyl; R.sup.7 is H, or --C(O)R.sup.5; and m is 1 to 20; provided that at least one of R.sup.1 and R.sup.4 is or includes a C.sub.8 to C.sub.22 group, are surfactants. A range of surfactant properties can be obtained by varying the molecules within these ranges. Especially where R.sup.2 is derived from a higher polyol e.g. sorbitol, R.sup.3 is C.sub.2 to C.sub.6, and the fatty terminal group is C.sub.8 to C.sub.14, the products can be highly water soluble and effective oil in water emulsifiers.