Abstract: Pd/Mm(mischmetal) rare earth films were prepared by magnetron sputtering technology,the crystal structure,morphology and electrochemical behavior of the asprepared films were investigated by using XRD,AFM and electrochemical measurement techniques including cyclic voltammetry and AC impedance.The results showed that Pd coatings is a kind of island structure with 30～50 nm in size.The electrochemical reduction or oxidation of hydrogen only occurred on the Pd coatings.The electrochemical impedance spectra of Pd/Mm film electrodes was composed of two semicircles,of which the low frequency zone is corresponded to the solid diffusion process of H atom in the film,and the high one to the electrochemical reaction on the surface of the electrode.The solid diffusion process of H atom in the inner rare earth layer is the ratecontrolled step.

Key words: Rareearth films, Electrochemical characteristics, Cyclic voltammetry