The cathode potential on the gas-evolving electrode in 0.5 M H2SO4 solution was measured under a uniform magnetic field. The current interrupter method allowed us to study the IR-drop and the supersolubility of dissolved hydrogen gas. MHD convection by Lorenz force slightly reduced the ohmic resistance between the working and reference electrode, considerably restricted the increase of supersolubility and simultaneously promoted the mass transfer coefficient of the dissolved gas above 50 mA cm(-2). Moreover, the supersolubility peak position displayed a strong dependence on the current density in the intermediate current density region from 5 to 30 mA cm(-2). The peak location shifted toward lower current density with increasing in magnetic flux density. Our data show that applying a magnetic field has a much greater effect on the supersolubility at intermediate current density region than the mass transfer coefficient. (C) 2009 Elsevier Ltd. All rights reserved.