Organic-inorganic type composite cation-exchanger poly-o-toluidine Zr(IV) tungstate was chemically prepared. The physico-chemical properties of the material were studied using FTIR, TGA, X-ray, SEM and EDX studies. The material was also characterized for its ion exchange properties to study its cation exchange behavior. It was observed that the material is thermally stable and possessed fast elution of exchangeable H+ ions. On the basis of K-d values, it was found highly selective for Hg(II) heavy toxic metal. The selectivity of this material for various metal ions varied depending upon the composition of eluting solvent. On the basis of selectivity studies, some important binary separations were also achieved to explore the potential application of this composite cation exchanger in environmental analysis of toxic heavy metals. (C) 2011 Elsevier B.V. All rights reserved.