Abstract: The behavior of hydrogen production on ZnO electrode during the electrolytic reduction of water was investigated by cyclic voltammetry (CV) and cathode polarization experiments combined with in situ Raman and photoluminescence spectroscopy. CV experiments indicate that hydrogen species prefers to diffuse into the ZnO bulk at negative potentials and occupies oxygen vacancies and interstitial sites. Meanwhile, the H₂O reduction is self-enhanced during the electroreduction process, as evidenced by the trace crossing of the CV curves and the chronoamperometric experiment. The influence of the H species on the ZnO electrode during the electrocatalytic processes was characterized by the in situ Raman and photoluminescence spectroscopies. These results help us to understand the hydrogen-related catalytic or electrocatalytic processes on ZnO surfaces.