A High-Temperature Metal-Air Battery (HTMAB) prototype based on a simple redox reaction between molten Sn and atmospheric oxygen at 800°C is presented, using yttria doped zirconia as solid electrolyte. Basic reversibility measurements indicate that the electrochemical reactions in the device are reversible with coulombic efficiencies higher than 95%. Significant influence of the cycling rate in the delivered capacity is detected; specifically it is increased from 8 to 90mAhcm−2 when reducing the discharge current from 12.5 to 0.56mAcm−2. EIS analysis performed over cycling shows that anode diffusion polarization increase due to sealing deficiencies is the main cause of degradation. Anyway, the electrochemical Sn oxidation/reduction reaction remains reversible for more than 4500 charge-discharge cycles and 6000hours operating at 800°C.