Microelectrochemical studies of hydrogen storage materials have been carried out using a microelectrode technique. A micromanipulator was used to contact single particles of Pd and LaNi5 in alkaline solutions with a carbon fiber filament. In this way cyclic voltammetry and potential step experiments were conducted and the apparent hydrogen diffusion coefficients in solid phases were determined. The current responses recorded as a function of time were analyzed with a spherical diffusion model : the diffusion coefficients were D = (4.3 +/- 1.9) x 10(-8) cm(2) s(-1) for a LaNi5 alloy particle and D = (2.8 +/- 0.2) x 10(-7) cm(2) s(-1) for a Pd particle, which were in good agreement with values reported in literature.