Fine Nb2O5 powder was filled into a basket-type cathode and immersed in molten CaCl2-0.5 mol% CaO at 1173K. Nb2O5 immediately reacted with CaO in the molten CaCl2 and formed calcium niobites that exhibited rod- or plate-like morphology. After the electrolysis of CaO with a graphite consumable anode, spherical particles of metallic niobium powder containing a residual oxygen concentration of 0.673 mass% O were obtained. (C) 2013 Elsevier Ltd. All rights reserved.