Solid state electroreduction of porous TiO2 to Ti immersed in CaCl2 melt occurs in electrochemical reactors using predominantly graphite rod anodes. Here we describe the solid state electroreduction of TiO2 in electrochemical reactors using graphite annulus anodes by both experiment and numerical simulation. This new experimental system shows electronic background currents that are similar to 3 times higher than that previously reported, experimental peak currents in excellent agreement with the current predicted in our thin layer three-phase interline (3PI) model, and large pores in Ti cathodes due to a Kirkendall-like effect. The latter increases the surface area of Ti cathodes indicating potential applications for enhancing bone cell ingrowth in medical implants as well as lowering the bone-metal stiffness mismatch. (C) 2015 Elsevier Ltd. All rights reserved.