Bis-betaine-amine oxides of the formula ##STR1## in which R is a saturated or an olefinically unsaturated hydrocarbon radical having 1 to 3 double bonds and 8 to 22 carbon atoms,n.sup.1 and n.sup.2 each is an integer of from 2 to 3, n.sup.1 and n.sup.2 optionally being identical or different,m.sup.1 and m.sup.2 each is an integer of from 1 to 4, m.sup.1 and m.sup.2 optionally being identical or different, anda, b, c and d, being identical or different, each is a number of from 1 to 5, with the proviso that the sum (a+b+c+d) is at most 10.The compounds are prepared from primary amines of the formula RNH.sub.2, by dicyanoalkylation, hydrogenation, ethoxylation, reaction with alkali metal salts of .omega.-halocarboxylic acids, and subsequent oxidation with hydrogen peroxide. They are surfactants of mild action and suitable for formulating cosmetic and industrial cleaning agents.