A continuous process for the bleaching of acid .alpha.-sulfo-fatty acid esters of predominantly C.sub.16-24 fatty acids comprising continuously adding the hydrogen peroxide bleach in aqueous solution as well as from 2% to 50% by weight, based on the sulfonated esters, of a C.sub.6-18 alkylbenzene sulfonic acid, to said raw, acid .alpha.-sulfo-fatty acid esters at a temperature of 40.degree. to 65.degree. C, continuously passing said mixture through a confined zone of dimensions sufficient to give a proper bleach retention time and continuously recovering bleached .alpha.-sulfo-fatty acid esters.