A new study is presented on the electro-deoxidation of porous TiO2 precursors in molten calcium chloride electrolytes. It is shown that by reducing precursor open porosity from standard values of >= 25% to similar to 11-12%, such that there is insufficient free volume to permit substantial incorporation of calcium, a new reaction pathway for electro-deoxidation is created. Kinetically and microstructurally it is more direct, with an effective pathway of TiO2 -> Ti2O3 -> TiO -> Ti metal at an inward-moving transformation front. CaTiO3, from limited calcium-incorporation reactions occurring at the beginning of the process, is shunted inwards and eventually reduced to Ti metal. The results indicate that there is greater freedom for precursor design and process optimisation than previously recognised. (C) 2011 Elsevier Ltd. All rights reserved.