A new type of polyelectrolyte complexes formed by hyperbranched poly(sulfone-amine) hydrochlorate and poly(sodium acrylate) has been reported. It has been found that the stoichiometry between polycation and polyanion is 1.16, which means that hyperbranched polyelectrolyte can also form the compact complexes in spite of the ill-defined structure. Moreover, the effect of various parameters, such as the architecture of poly(sulfone-amine), molecular weight of polymer, concentration and low molecular salt, on the complexation is also discussed. (c) 2007 Wiley Periodicals, Inc.