The electrochemical performance of fluorinated carbon nanotube (CFx, x = 0.31) is investigated as oxygen electrode for Li-O-2 battery. When compared with conventional carbon nanotube (CNT)-based electrode in Li-O-2 battery, the battery with CF0.31-based oxygen electrode exhibits significantly enhanced specific capacities and high-rate capability. For CF0.31 based Li-O-2 battery, two electrochemical reactions (oxygen reduction reaction and CF0.31 conversion reaction) occur during discharge process. The defects on the carbon nanotube after fluorination improves electrocatalytic activity of oxygen reduction on the material, and the loosely discharge products coated on the cathode due to the conversion of CF0.31 and reduction of oxygen occurred simultaneously provide further reactive sites on CF0.31 for oxygen reduction, is one of the main reasons for the enhanced electrochemical performance of fluorinated CNT. CF0.31 is shown as one promising material as oxygen electrode which can exhibit a good rate performance and a high specific energy density. (C) 2012 Elsevier Ltd. All rights reserved.