NaOH as electrolyte:Anode: H2 + 2OH- → 2H2O + 2e-Cathode: O2 + 2H2O + 4e- → 4OH-Phosphoric acid as electrolyte:Anode: H2 → 2H+ + 2e-Cathode: O2 + 4H+ + 4e- → 2H2O