SnSO4 was employed as an anode-active material for rechargeable batteries, where Sn4+ and Sn2+ ions are reduced to Sn2+ and Sn, respectively during charge while the inverse reactions occur during discharge. Undesired hydrogen production was substantially avoided by adjusting the charge voltage to 1.5 V. The resulting cell functioned as a battery with an electrical capacity of 258 mA h g(-1) at 10 mA cm(-2) and as a fuel cell with power densities of 55-125 mW cm(-2) at 0.8 V.