The apparent interdiffusion coefficient has been determined from the bulk concentration of electrolyte solution and interdiffusion time. The integral interdiffusion coefficient can be estimated from the results using the Donnan membrane equilibrium. The data show that the interdiffusion is controlled by the component with low concentration, and the relationships between the apparent interdiffusion coefficient and temperature can be expressed by an Arrhenius plot for various interdiffusion systems. In the cation exchange membrane Selemion CMV the apparent interdiffusion coefficient DAB and interdiffusion activation energy EAB for various systems have magnitudes in the relative order DH-li < DH-Na < Dh_k and EH_Li > EH_Na > EH_K, respectively. The interdiffusion of counterions is independent of the kinds of co-ions at low concentration of the solution. There is an increase of integral interdiffusion coefficient and a decrease of interdiffusion activation energy with increasing bulk concentration of the electrolyte solution.