A terpolymer resin was synthesized by the condensation of 2,2'-dihydroxybiphenyl with guanidine and formaldehyde in the presence of 2M HCl as a catalyst. The resin obtained was characterized on the basis of elemental analysis, infrared spectroscopy, NMR spectroscopy, ultraviolet-visible spectroscopy, and thermogravimetric analysis/differential thermal analysis. The number-average molecular weight was determined by nonaqueous conductometric titration. A thermal study of the resin was carried out to determine its mode of decomposition, activation energy, order of reaction, frequency factor, entropy change, free energy, and apparent entropy change. The Freeman-Carroll and Sharp-Wentworth methods were applied for the calculation of the kinetic parameters, and the data from the Freeman-Carroll method were used to determine various thermodynamic parameters. The chelation ion-exchange properties of this resin were studied for Fe3+, Cu2+, Ni2+, Co2+, Zn2+, Cd2+, and Pb2+ ions. A batch equilibrium method was used in the study of the selectivity of the metal-ion uptake that involved 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+ ions than for the other metal ions in this study. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 118: 1969-1978, 2010