The energy density of current rechargeable lithium batteries is limited by the capacity of the LiCoO2 positive electrode (140 mA h g(-1)). The best intercalation electrode is only likely to increase this by a factor of 2 (1Li/Tm). Replacing the intercalation cathode with an O-2 electrode could raise the capacity 5-10-fold. Here, we explore the influence of the catalyst could have on the performance of a non-aqueous O-2 electrode on a Li/O-2 cell. Of the catalysts studied the highest initial capacity was observed with Fe2O3 (2700 mA h g(-1)), the highest capacity retention with Fe3O4, CuO and CoFe2O4 (6.67% per cycle). Co3O4 gives the best compromise between initial capacity (2000 mA h g(-1)) and capacity retention (6.5% per cycle), as well as the lowest charging voltage 4 V. All capacities expressed per gram of carbon and at a rate of 70 mA g(-1). (C) 2007 Elsevier B.V. All rights reserved.