The electrolytic deuterium separation factors were measured in KOH aqueous solution at 298 K for the two iron films electrodeposited in no magnetic field (film (a)) and a magnetic field of 0.5 T (film (b)). The separation factors were higher for film (b) (9.8-12.3) than those for film (a) (8.7-10.2). From the exchange current density and the real surface area, it was found that film (b) has higher electrocatalytic activity for the hydrogen evolution reaction. The SEM images showed cracks on the whole surface for film (b), which suggests that the strain energy is stored. The improved electrocatalytic activity for the HER is explained by the preferred adsorption of proton due to the strain energy in the film. The increase of the deuterium separation factor is also explained by the electrocatalysis activated by the strain energy. (C) 2004 Elsevier Ltd. All rights reserved.