Hydrophillic macronet resins were prepared via a route which includes simultaneous sulphonation and cross-linking of styrene-acrylonitrile copolymer and polystyrene foam. Chlorosulphonic acid was employed as both the sulphonating reagent for the introduction of the sulphonic acid group on styrene units and the medium for the formation of sulphone-type cross-links. Controlled cross-linked structures were achieved by the parallel participation of acetic acid or acetic anhydride as sulphone cross-bridging regulators. The reaction yield, as well as the properties of the formed gels, were studied in respect to the cross-linking regulator concentration and the chlorosulphonic acid flow rate. Both strongly and weakly acidic ion-exchangers on the same substrate were achieved when styrene-acrylonitrile copolymer was used as a raw material. The synthesized macronet ion-exchangers were found to exhibit high swelling abilities and intermediate ion-exchange capacities while scanning electron microscopy (SEM) revealed their morphology.