Electrochemical characterization of Nafion membrane on the basis of membrane potential and membrane conductance measurements has been carried out to investigate variation in its permselectivity with composition of the electrolyte solutions. Possibility of prevention of reduction in the ion selective character of the membrane with increase in concentration upon immobilization of sodium dodecyl sulphate and dodecyl alcohol has been explored. Correlation between the extent of immobilized surfactants and improvement in ion selectivity of the membrane has also been attempted.