Terpolymers have been prepared by the condensation of 2,4-dihydroxyacetophenone (2,4-HA) and dithiooxamide (D) with formaldehyde (F) in the presence of hydrochloric acid as catalyst with varying the molar proportions of the reactant. Compositions of the terpolymer have been determined by elemental analysis. The number average molecular weight (M) over bar (n) has been determined by conductometric titration in nonaqueous medium. Intrinsic viscosities of the solution of the terpolymer have been determined in N,N-dimethyl formamide (DMF). The terpolymers have been characterized by UV-visible, IR, and proton NMR spectra. Chelation ion-exchange properties have also been studied employing the batch equilibrium method. It was employed to study selectivity of metal ion uptake over a wide pH range and in media of various ionic strength. The overall rate of metal uptake follows the order: Fe3+ > Cu2+ > Ni2+ > Co2+ = Zn2+. (c) 2008 Wiley Periodicals, Inc.