Quaternary surfactants of the formula (I), wherein R1CO is a linear or branched, saturated or unsaturated, optionally hydroxy-functionalized acyl radical having 6 to 22 carbon atoms and 0, 1, 2 or 3 double bonds, R2 is a CH2COOH radical, an alkyl radical having 1 to 4 carbon atoms, a CH2CH2OH or a CH2CH2OCH2CH2OH group, and X is halide, alkyl sulfate, alkyl carbonate or alkyl phosphate, are useful as surfactants in cosmetic and pharmaceutical preparations. Aqueous solutions above 50% by weight of the surfactants are flowable and pumpable.