The influence of Al2O3 concentration on the direct electrochemical reduction of porous vanadium sesquioxide precursors in molten Na3AlF6 was investigated by constant voltage electrolysis and cyclic voltammetry. The products obtained by electrolysis at various Al2O3 concentrations were examined by XRD and SEM. Specifically, the morphologies of the outer metal layer initially formed were characterized by SEM and EDS, also their effects on the electrolysis process were systematically studied. The results indicate that the Al2O3 concentration in molten Na3AlF6 has a significant impact on the reduction process. When 0.5 mass% Al2O3 is added into molten Na3AlF6, the reduction rate of V2O3 can be improved because of the appropriate increase of aluminium reductant and relatively high oxide ion transfer rate. However, a high Al2O3 concentration (1.0-3.0 mass%) causes the massive precipitation of aluminium at cathodic outer metal layer and further forms Al-V alloy, causing the densification of the outer metal layer and hampering the reduction reaction kinetics. (C) 2018 Elsevier Ltd. All rights reserved.