Terpolymer resins, synthesized by the condensation of salicylic acid and melamine with formaldehyde in the presence of an acid catalyst, proved to be a selective chelating ion-exchange polymer for certain metals. The chelating ion-exchange properties of this polymer were studied for Cu2+, Ni2+, Co2+, Zn2+, Fe3+, Cd2+ and Pb2+ ions. A batch equilibrium method was employed in the study of the selectivity of metal ion uptake involving the measurements of the distribution of a given metal ion between the polymer sample and a solution containing the metal ion. The study was carried out over a wide pH range and in media of various ionic strengths. The terpolymer showed a higher selectivity for Fe3+, Cu2+ and Ni2+ ions than for Co2+, Zn2+, Cd2+ and Pb2+ ions. (C) 2002 Elsevier Science B.V. All rights reserved.