A water-soluble cationic copolymer dispersion was prepared by the polymerization of the cationic monomer (2-methacryloyloxyethyl)trimethyl ammonium chloride and acrylamide initiated with Co-60 gamma-rays. The polymerization was carried out in a salt solution that did not dissolve the resulting copolymer and in the presence of a polymeric dispersant that was soluble in the salt solution. The polymerization conversion was studied gravimetrically. The bulk viscosity of the copolymer dispersion was determined with a rotation viscometer. The intrinsic viscosity of the copolymer was measured viscometrically, and the particle size was determined with an optical microscope. The influence of some conditions on the copolymerization was studied, including the irradiation dose, dose rate, concentrations and compositions of the monomers, dispersant content, and types and contents of the inorganic salts. The flocculating characteristics of a synthetic cationic copolymer dispersion were also briefly investigated. The optimal conditions for polymerization were summarized, and some aspects of the polymerization mechanisms were examined. (C) 2003 Wiley Periodicals, Inc.