Disclosed is an acid-funtionalized polyurethane adduct and a process for the preparation of such adduct. The adduct having a linear or preferably branched structure comprises a plurality of internal urethane linkages and one or more terminal carboxylic acid groups per molecule. Such acid-funtionalized polyurethane adducts find value in the manufacture of crosslinked aqueous rubber latexes such as might be used in paint compositions.