The effect of externally imposed magnetic fields on the iron anodic process in 0.5 mol dm(-3) H2SO4 solution was studied experimentally with the potential-sweep method and holographic microphotography. The mass transport rate was increased by the magnetic field. The presence of the magnetic field had no obvious effect on the dissolution of iron, but in the prepassive range, the increase of the mass transport by the magnetohydrodynamic (MHD) flow ultimately resulted in the increase of iron dissolution.