A process for the preparation of sulphonated distyryl-biphenyl compounds of formula (1), in which R.sub.1 and R.sub.2, independently, are hydrogen, C.sub.1 -C.sub.5 -alkyl, C.sub.1 -C.sub.5 -alkyl or halogen, and M represents Li, K, an alkaline earth metal or ammonium, characterized by, firstly, reacting a compound of formula (2) with a di- or trialkylamine containing 6-12 carbon atoms in each alkyl group, in a two-phase system consisting of strong aqueous mineral acid and a water immisicible organic solvent and, secondly, reacting the resulting lypophilic ammonium salt with LiOH, KOH, an alkaline earth metal hydroxide, ammonia, a mono-, di- or trialkylamine or a tetraalkylammonium hydroxide, all containing 1-4 carbon atoms in each alkyl group; mono-, di- or tri(C.sub.2 -C.sub.4)alkanolamine, morpholine, piperdine or pyrrolidine. ##STR1##