A water-soluble cationic flocculant, the copolymer of acrylamide (AM) and acryloylamino-2-hydroxypropyl trimethyl ammonium chloride (AMHP), has been synthesized through dispersion polymerization in aqueous ammonium sulfate ((NH4)(2)SO4) solution. The polymerization was initiated by potassium persulfate (KPS) using poly(2-methylacryloylxyethyl trimethyl ammonium chloride) (PDMC) as the stabilizer. The copolymer obtained was characterized using Fourier-transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, colloidal titration and optical microscopy. Its flocculation properties were evaluated with 0.25 wt% kaolin suspensions using a standard jar test. The zeta potential of the supernates at different flocculant dosages was measured simultaneously. The results demonstrate the superiority of the copolymer over the commercial polyacrylamide as a flocculant. (C) 2009 Elsevier B.V. All rights reserved