The formation and complexing behaviors of non-soluble polyelectrolyte complexes (nPECs) between ammonium polyacrylate (A40) and poly(diallyldimethylammonium chloride) (PDC) polyelectrolytes at different A40/PDC mass ratios, pHs and KNO3 concentrations were studied using particle size and zeta potential measurement techniques. It was found that the particle size distributions and surface charge behaviors of the formed nPECs were related to the mass ratio of participating polyelectrolytes and KNO3 concentrations. Without addition of KNO3, there was no nPECs formed at a mass ratio of 0.1. Both fine and large nPECs were formed at mass ratios of 0.2 and 0.6 while only fine nPECs formed at a mass ratio of 0.4. Increasing the mass ratio from 0.8 had no significant effect on particle size distribution. The observed complexing behaviors were related to the histories of charge neutralization degree of PDC and the surface zeta potentials of nPECs. The addition of electrolyte would result in bigger nPECs attributable to the shielding effect and weakened electrostatic interaction for polyelectrolytes and nPECs, and hence the linkage of nPEC became possible. The pH changes affected the surface zeta potentials of nPECs due to the variation in ionization of A40 molecules. (c) 2005 Elsevier Ltd. All fights reserved.