Products of electrolytic breakdown of water are molecular oxygen (O2) and molecular hydrogen (H2), as described by the New Mexico Solar Energy Association. The process follows chemical equation: energy (electricity) + 2 H2O = O2 + 2 H2.
According to the London South Bank University, water electrolysis is a sum of two redox reactions. At the cathode, water accepts free electrons from the current circuit and undergoes reduction, producing hydrogen and oxonium ions: 4e- + 4H2O = 2H2 + 4OH-. At the anode, water is oxidized, producing oxygen, hydrogen ions and free electrons that re-enter the circuit: 6H2O = O2 + 4H+ + 4e-.