Michelson interferometer was developed to measure the concentration profile within diffusion layer in a galvanic displacement reaction system. A steady diffusion layer was achieved near the working electrode due to natural convection, viz., at long time and without any forced hydrodynamics. The concentration difference within diffusion layer is directly proportional to the distance of interference fringe deviated from linear one of bulk solution. Therefore, the concentration profile in diffusion layer can be measured from interference fringe. The validity of theory model deduced by Amatore and co-workers was further validated in our experiment. (c) 2008 Elsevier B.V. All rights reserved.