A novel type of rechargeable sodium–air battery working at room temperature is constructed and examined for the first time. The typical gravimetric capacities of the air electrodes (diamond-like carbon thin films) are 1884 mAh/g (565 μAh/cm2) at 1/10 C and 3600 mAh/g (1080 μAh/cm2) at 1/60 C, respectively, which are significantly superior to intercalation-based cathode materials for rechargeable sodium or lithium batteries ever reported. The electrochemical reaction of the sodium–air battery is investigated. The high reversible capacity and relevant high output voltage (about 2.3 V) of the room temperature sodium–air battery make it a potential
alternative battery in the future.