A new composite cation exchange material poly-o-toluidine stannic molybdate was synthesized by the incorporation of an organic polymer poly-o-toluidine into the matrices of inorganic precipitate of stannic molybdate. The experimental parameters such as concentration, mixing ratio and pH were established for the synthesis of the material. The material was found to be granular and can be conveniently used in column operations. The newly synthesized composite material exhibits improved thermal stability, ion exchange capacity and selectivity for toxic heavy metal ions. The material is characterized using various analytical techniques like FTIR, TGA, DTA, XRD, SEM, TEM and elemental analysis. The X-ray diffraction study showed semicrystalline nature of the material. The pH titration studies revealed monofunctional weak acid behavior of the exchanger. The elution behavior of the exchanger was also examined. The distribution coefficient studies of metal ions on the material were performed in different solvent systems and the material was found to be selective for Hg2+ and Pb2+ ions. On the basis of distribution coefficient values, some analytically important binary separations of metal ions viz. Al3+-Hg2+, Cu2+-Hg2+, Cu2+-Th4+, Zn2+-Hg2+, Bi3+-Hg2+, Cd2+-Pb2+ were achieved on poly-o-toluidine stannic molybdate columns. Hg2+ and Pb2+ ions were also selectively separated from synthetic mixtures of metal ions. In order to demonstrate the practical utility of the material, quantitative separations of Hg2+ from thermal power plant effluents and of Pb2+ from lead storage battery industry wastes have been achieved. (C) 2010 Elsevier B.V. All rights reserved.