Spent lithium ion batteries (SLIB) are potential environmental hazards and if not recycled waste natural resources. We demonstrate for the first time a process to directly reuse Ni-Co-Mn oxides from SLIBs to prepare air electrodes based on a simple thermal treatment method. The effects of heating temperature and duration on the properties of Ni-Co-Mn oxides using scanning electron microscopy and X-ray diffraction is described. The Ni-Co-Mn oxide materials were found to be mainly LiNi1-x-yCoxMnyO2, with the α-NaFeO2-type structure (PDF file: 01-075-9200). After heat treatment at 600 o C, the Ni-Co-Mn oxides exhibited the spinel structure (PDF file: 00-048-0261). Electrochemical tests revealed that the Ni-Co-Mn oxides heat-treated at 600 o C for 300 minutes, exhibited remarkable bifunctional catalytic activities towards the oxygen evolution and oxygen reduction reactions in aqueous KOH electrolyte. The electron transfer number on Ni-Co-Mn oxide electrode for oxygen reduction was about 3.6. When these Ni-Co-Mn oxide powders were applied in an air battery, the energy efficiency was 75 % at a current density of 10 mA cm-2 , at room temperature.