This work shows that the transfer current recorded during a chronoamperometry of an electrodiffusion test is not governed by a simple law of conduction (Ohm's law), but it is influenced by the electrical double layer which is quantified by the parameter chi. Taking into account the effect of this double layer, we suggest a model that allows us to extract the transfer current generated by chloride diffusion. The flux of chloride ions is obtained without dosage in the downstream of the electrodiffusion cell, but from simple chronoamperometry.