The present study indicated that stable blended collodion/Nafion membranes can be obtained by adding Nafion solution to 50% in volume to collodion solution, The mixed solution beyond the critical volume of Nafion solution leads to the bringing about of phase separation. The blended membranes obtained as the cast membrane indicated almost the same permselectivity as ordinary cation exchange membrane. Regarding three different membranes including pure Nafion membrane, water flow and KCl flows were investigated systematically, The transport properties of water and KCl across the composite membrane and other characteristics such as water content in the membrane depended on the quantities of Nafion component and they increased with the increase in Nafion component. It was suggested that the transport properties changed according to the existence of water accompanied by Nafion polymer in the composite membrane. In addition, the effective charge densities of composite membranes were estimated from the membrane potential measurements and were compared with conventional cation exchange membrane. As a whole, the composite membranes indicated membrane performance comparable to the commercial ion exchange membranes.