Non-aqueous lithium-oxygen batteries have been regarded as one of the most promising alternative devices for electric vehicles owing to their ultrahigh theoretical energy densities. However, the sluggish reaction kinetics associated with Li2O2 deposition and oxidization during discharge and charge have severely limited the development of this type of battery. Here, mesoporous ultrafine Ta2O5 nanoparticles with high specific surface area and abundant oxygen vacancies are synthesized and applied to a non-aqueous Li-O2 battery. With this novel catalyst, the non-aqueous Li-O2 battery is capable of delivering a much higher reversible capacity of ∼13000 mAh g−1 at a current density of 500 mA g−1 with a lower discharge and charge over-potential of ∼0.18 V and ∼1.01 V, respectively. In addition, the cycling number of the battery increases up to 100 with a coulombic efficiency of 100% at the current density of 500 mA g−1, whereas the battery without this catalyst suffers from severe decay after only 40 cycles. Moreover, when the current density increases from 500 to 1000 mA g−1, the battery still can be operated for 76 times with no degradation, indicating its excellent rate capability and stability.