The cyclic voltammetry, open current potential-time curve after potentiostatic electrolysis, the current-time curve at potential step, XRD, EDAX and EPMA were used to study the electrode process of Ho3+ reduction on nickel electrode in molten KCl-HoCl3 and the phases of surface alloy layer. The Ho-Ni alloys were deposited when Ho3+ was reduced on the nickel electrode. The free energies of formation for the intermetallic compounds between Ho and Ni, the diffusion coefficients and diffusion activation energy of Ho atom in the alloy phase were determined.