The systems studied are constituted of an aqueous solution of a potassium halide in contact with a nitrobenzene solution of hexadecyl trimethyl ammonium picrate. The inorganic salt is very slightly soluble in nitrobenzene while the organic electrolyte is practically insoluble in water. The variation of the interfacial tension under galvanostatic conditions is related to the change of the ionic concentration in the interfacial layer due to the ion transfer between the two immiscible solutions; the current is only carried across the interface by the halide ions passing from the water to the nitrobenzene. A quantitative analysis of the effect is presented for different current densities.