A new water-soluble amphoteric copolymer (PAC) was synthesized and evaluated as a dispersion agent for cement particles PAC was prepared from acrylamide and 2-(3-carboxyacryloyloxy)-N-(carboxymethyl)-N,N-di-methyl ethanaminium (CAC) through free-radical polymerization. The structure of the prepared polymer was verified by the IR spectra The dispersion properties of PAC were evaluated by the minislump test on cement pastes The test results indicate that this copolymer could disperse the cement particles and improve the fluidity of the cement pastes Compared with a commercial superplasticizer, sulfonated naphthalene formaldehyde condensate, PAC showed better dispersion properties This polymer, with about 16.7% CAC and a weight-average molecular weight of about 1 x 10(5), was most effective in dispersing cement particles and enhancing the fluidity of the cement pastes. This was attributed to the interaction and adsorption behavior of this admixture with cement particles (C) 2010 Wiley Periodicals, Inc J Appl Polym Sci 118 1313-1319, 2010