Lithium titanium oxide (LTO) with a ramsdellite structure is an advantageous anode for lithium ion secondary batteries, because of its positive potential, which is beneficial for safety reasons. In addition, compared with other titanate anodes, it has a superior theoretical capacity of 321 mA h g(-1), which is close to the capacity of a practical carbonaceous anode. Our study showed that this ramsdellite-type LTO had a high discharge capacity that is stable at 250 mA hg(-1) at a current density of 1 mA cm(-2). However, this high capacity is only achieved by employing as-synthesized ramsdellite LTO powder. When the same powder was stored and the same evaluation was carried out, the resulting capacity was 200 mA hg(-1), which is lower than the capacity of as-synthesized powder. An annealing applied to the ramsdellite LTO powder appeared to restore the capacity loss after storage. Annealing at 250 degrees C for 5h produced the best performance, which was even better than that obtained using the as-synthesized ramsdellite LTO powder. Moreover, we investigated the surface property of ramsdellite LTO and found that the presence of a carbon derivative is apparently responsible for blocking the Li ions insertion/extraction, and thus reducing the capacity. (C) 2011 Elsevier B.V. All rights reserved.