The effect of high magnetic fields on interfacial reactive diffusion in liquid/solid (Al/Cu) couples was experimentally investigated at a temperature of 973 K. Regardless of any magnetic field compound layers, consisting of the delta, xi(2), eta(2) and theta phases were produced at the interface. The magnetic flux density, B, exerted a non-monotonic influence on the growth of the diffusion layers. Moreover, the mean thickness of the diffusion layers (parallel to B) was found to be always greater than that of the diffusion layers (perpendicular to B) under the applied magnetic fields. These phenomena should be attributed to the effects of two types of the Lorentz force under a uniform high magnetic field on diffusion behavior. In addition, the growth of intermetallic phases could be retarded by a magnetic field gradient due to the magnetic force in the axial direction. (C) 2009 Elsevier B.V. All rights reserved.