Single Reversible Fuel Cell Produces .75 volts. This reversible fuel cell offers students the option of experimenting with pure oxygen or air. As an electrolyser it operates at 2 Watts. The ideal amount of voltage for electrolysis is 1.2 Volts, but for convenience 1.5 volts from a AA battery will be acceptable. This product is the fuel cell only. For storage cylinders, wiring, etc. consider purchasing a complete kit.