Autonomous and portable electronic devices require cheap energy storage units of ever-increasing power and energy densities. Zinc/halogenate flow battery is proposed as a new type of reserve or emergency power supply unit. The battery uses a mechanically rechargeable zinc anode in contact with neutral aqueous salt electrolyte, cation-exchange membrane, and a carbonaceous flow through cathode, at which aqueous acidified halogenate is reduced to halide in a six-electron process. A new multielectron oxidizer, aqueous iodate, that can be used in other electrochemical power sources, is introduced. It is shown that iodate can be readily reduced in acidic media at cheap carbonaceous electrodes. Electrochemical experiments with stationary and rotating disk glassy carbon electrodes reveal that in acidic aqueous electrolytes reduction of iodate can be as fast as earlier studied reduction of bromate. Theoretical energy densities per reactants of Zn/bromate and Zn/iodate batteries are 1.2 and 1.45 kWh L⁻¹, respectively. Area-specific power of the single cells of these batteries reaches 0.57 W cm⁻² at 50 °C.