An electrically conducting `organic–inorganic' crystalline type composite cation-exchange material, the polypyrrole/polyantimonic acid system was prepared by incorporating polypyrrole into an inorganic precipitate of polyantimonic acid. The temperature dependence of the electrical conductivity of this composite system was measured on compressed pellets by using a 4-in-line-probe dc electrical conductivity-measuring instrument. The conductivity values lie in the semiconductor region, i.e., they are of the order of 10−5–10−4 S cm−1 and follow the Arrhenius equation. The energy of activation of electrical conduction was also calculated. This system also possessed an improved ion-exchange capacity, high chemical and thermal stabilities, reproducibility and selectivity for some specific metal ions. Kinetic studies of exchange for some divalent metal ions of alkaline earths and transition metals were carried out under conditions favoring a particle diffusion-controlled ion-exchange phenomenon and some physical parameters such as the self diffusion coefficient D 0, the energy of activation E a and the entropy of activation ΔS * were determined.