Polypyrrole Th(IV) phosphate, an electrically conducting 'organic-inorganic' cation-exchange composite material was prepared by the incorporation of an electrically conducting polymer, i.e., polypyrrole, into the matrix of a fibrous type inorganic cation-exchanger thorium(IV) phosphate. The composite cation-exchanger has been of interest because of its good ion-exchange capacity, higher chemical and thermal stability, and high selectivity for heavy metal ions. The temperature dependence of electrical conductivity of this composite system with increasing temperatures was measured on compressed pellets by using four-in-line-probe dc electrical conductivity measuring instrument. The conductivity values lie in the semiconducting region, i.e., in the order of 10(-6) to 10(-4) S cm(-1) that follow the Arrhenius equation. Nernst-Plank equation has been applied to determine some kinetic parameters such as self-diffusion coefficient (DO), energy of activation (E-a, and entropy of activation (Delta S*) for Mg(II), Ca(II), Sr(II), Ba(II), Ni(II), Cu(II), Mn(II), and Zn(II) exchange with H+ at different temperatures on this composite material. These results are useful for predicting the ion-exchange process occurring on the surface of this cation-exchanger. (C) 2007 Wiley Periodicals, Inc.