Lithium-oxygen battery has high energy density which is considered as promising candidate for next-generation energy storage system. One of the major challenges for Li–O2 battery is exploring efficient catalysts for the decomposition of Li2O2 and by-products. In this work, a robust cathode employing RuO2·nH2O clusters anchored on the carbon nanofibers (RNCs@CNFs) is fabricated for Li–O2 battery. RNCs demonstrate an excellent oxidation activity towards both Li2O2 and Li2CO3 during the oxygen evolution reaction (OER). The unique structure of RuO2·nH2O clusters also alleviate the deactivation caused by the coverage of active sites. As a result, the as-built battery exhibits a high specific capacity, a superior rate capability and an excellent cycling stability with low overpotentials. After 200 cycles, new Li anode is replaced and the battery continues 100 cycles without attenuation at a limited capacity of 1000 mAh g−1 and a current of 200 mA g−1. These results provide necessary information for the development of efficient cathode catalysts for the decomposition of Li2O2 and Li2CO3 in Li-air batteries. •A robust cathode employing RNCs@CNFs is fabricated.•RNCs@CNFs accelerate the decomposition of both Li2O2 and Li2CO3.•The unique structure of RNCs alleviates the deactivation of the carbon-based cathode.•The cathode exhibits extremely long cycle life.