[en] compsite materials formed by the combination of multivalent metal acid salts and organic polymers provide a new class of (organic-inorganic) hypride ion exchangers with better mechanical and granulometric properties, good ion-exchange capacity, higher chemical and radiation stabilites, reproducibility and selectivity for heavy metals. this material was characterized using X-ray (XRD and XRF), IR, TGA-DTA and total elemental analysis studies. on the basis of distribution studies, the material has been found to be highly selective for pb(II). thermodynamic parameters (i.e δG⁰, δ S⁰ and δH⁰) have also been calculated for the adsorption of Pb²⁺, Cs⁺, Fe³⁺, Cd²⁺, Cu⁺², Zn²⁺, Co²⁺ and Eu³⁺ions on polyacrylamide Sn(IV) molybdophosphate showing that the overall adsorption process is spontaneous endothermic. the mechanism of diffusion of Fe³⁺, Co²⁺, Cu⁺², Zn²⁺, Cd²⁺, Cs⁺, Pb²⁺ and Eu³⁺ in the H-form of polyacrylamide Sn(IV) molybdophosphate composite as cation exchanger was studied as a function of particle size, concentration of the exchanging ions, reaction temperature, dring temperature and pH. the exchange rate was controlled by particle diffusion mechanism as a limited batch techneque and is confirmed from straight lines of B versus 1/r² polts. the values of diffusion coefficients, activation energy and entropy of activation were calculated and their significance was discussed. the data obtained have been comared with that reported for other organic and inorganic exchangers.