8-Hydroxyquinoline-5-sulfonic acid-thiourea-formaldehyde copolymer resins were synthesized through the condensation of 8-hydroxyquinoline-5-sulfonic acid and thiourea with formaldehyde in the presence of hydrochloric acid as a catalyst and with various molar ratios of the reacting monomers. The resulting copolymers were characterized with UV-visible, IR and 1H-NMR spectral data, employed to determine the reactivity of monomers. The average molecular weights of these resins were determined with vapor pressure osmometry and conductometric titration in a nonaqueous medium. The chelation ion-exchange properties were also studied with the batch equilibrium method. The resins were proved to be selective chelating ion-exchange copolymers for certain metals. The chelation ion-exchange properties of these copolymers were studied for Cu 2þ , Ni 2þ , Co 2þ , Pb 2þ , and Fe 3þ ions. The study was carried out over a wide pH range and in media of various ionic strengths. The copolymers showed a higher selectivity for Fe 3þ ions than for Cu 2þ , Ni 2þ , Co 2þ , and Pb 2þ ions.