A high performance CoO/carbon nanofibers (CNF) composite catalyst was synthesized for Li-O2 batteries. For comparison, CoO/BP2000 and CoO/MWNTs were also prepared and investigated to study the influence of carbon supports on the electrochemical performance of the composite catalysts. Electrochemical tests showed that the Li-O2 battery with CoO/CNF demonstrated obviously enhanced electrochemical performance than the batteries with CoO/BP2000 and CoO/MWNTs catalysts, which delivered a first discharge capacity of 3882.5mAhgcat −1 and remained about 3302.8mAhgcat −1 after 8 cycles in the voltage range from 2.0 to 4.2V. More importantly, the cycle stability of the Li-O2 battery with CoO/CNF could maintain over 50 cycles when cycled at a fixed capacity of 1000mAhgcat −1. The unique porous nanofiberous structure of CoO/CNF greatly contributed to its high electrocatalytic performance.