Kinetics of the cathode process on tungsten in the KF-AlF3-Al2O3 melt and slurries was studied by means of voltammetry. The effects of the potential sweep rate (0.01-2.0 V/s), temperature (715, 750, 800°С), and Al2O3 suspension content (0, 30, and 45 wt %) in the cell on the kinetics were tested. Diffusion coefficients of the electroactive ions at the aluminum elecrowinning from the KF-AlF3-Al2O3 melt and suspensions were estimated. It was shown that the adding of the Al2O3 slurry in the KF-AlF3-Al2O3 melts increase the diffusion difficulties of the process under study.