There is no general agreement on the experimental conditions used in the hydrogen electrochemical permeation method. Particulary, the necessity of a palladium coating on steel is not yet recognized. To answer some questions concerning the boundary conditions, experiments were carried out on pure iron and low alloyed steels without palladium coating. it is shown clearly that in this case surface phenomena are not controlled. Especially, the passivation layer on the exit side induces variation of the hydrogen concentration on this side with time. Consequently no quantitative evaluation can be made for diffusion parameters, as long as the mathematical model issued from the usual stationary boundary conditions is used.