Electrochemical properties of cation-exchange membranes prepared from mixture of sulfonate-containing polyamide and weakly interacting with it PVC (heterogeneous membranes) and strongly interacting with it poly(m-phenyl isophthalamide) (homogeneous membranes) were studied. Sulfonde-containing aromatic polyamide was synthesized from sodium salt of 4,4'-diaminodiehenylamine-2-sulfonic acid and chloroanhydride of isophthalic acid. As compared with homogeneous membranes, heterogeneous membranes show a sharp increase in specific electroconductivity in a wide range of static exchange capacity (10-50 times). This behavior was rationalized by the development of canals with increased water content in heterogeneous membranes.