Particulate materials of natural origin, sulfite cellulose and two kaolinite clays, were modified by the formation of nonstoichiometric polyelectrolyte complex on the surface of particles. This resulted in positive surface charge on cellulose and clays. Modified materials as well as selected commercial polymers were used as sorbents for removal of anionic, nonionic, and cationic surfactants from aqueous solutions. It was stated that cationic surface modification of cellulose and kaolinite clays resulted in a significant increase of sorption rate and degree of removal of oppositely charged anionic surfactants. (C) 2004 Wiley Periodicals, Inc.