Calcium boride (CaB6) crystal powder was prepared by electrolysis in a molten salt electrolyte of 50% CaCl2-50% NaCl (molar%) at 750 A degrees C. The current efficiency and product formation rate during the electrolysis were studied based on the experimental data. The electrolytic products including the CaB6 crystal particles were analyzed by X-ray diffractometry and scanning electron microscopy. Cyclic voltammetry was used to study the electroreduction mechanism of the reactive species. The results demonstrate that the rate of electrolytic reduction is determined by the diffusion rate of the reactive species in the molten salt.