The influence of the anodic polarization on the hydrogen diffusion flux i(H) through a steel membrane has been studied in the C2H4(OH)(2) + H2O + H+ solutions containing 1 mM thiourea or sodium hydroarsenate. The electrolyte composition is x M HCl + (1-x) M LiCl, where x = 0.01-0.99 mol/l. The dependence of the hydrogen diffusion flux through the membrane on the anodic polarization value passes through a maximum independently of a nature of the solvent, a character of the volume or surface solvation, a nature of the rate determining step of the hydrogen evolution reaction, a presence or an absence of the hydrogenation stimulators. It does not connect with the pH value. It is caused by the different dependence of two forms of Had, on the surface charge of the entrance membrane side. (c) 2006 Elsevier B.V. All rights reserved.