A key issue to design highly efficient photoelectrodes for hydrogen production is how to prohibit the rapid carrier recombination. In order to use the visible light and reduce the recombination of electrons and holes, reduced TiO 2-x /BiOCl heterojunctions are successfully synthesized and the photoelectrodes are assembled in this work. The effects of various Bi/Ti molar ratios on the structural, morphological, optical, photoelectrochemical and photocatalytic activities of the resultant samples are investigated systematically. The TiO 2-x nanoparticles contain Ti 3+ , Ti 2+ , and oxygen vacancies (Ov), while the BiOCl nanosheets exposed {001} facet. Ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS) results indicate that the existence of Ti 3+ , Ti 2+ and Ov expand the light-response range. Linear scan voltammetry and electrochemical impedance spectroscopy results indicate that more efficient electron transportation is presented in the heterojunctions with the appropriate Bi/Ti molar ratio. Consequently, the reduced TiO 2-x /BiOCl heterojunction with the most appropriate Bi/Ti molar ratio exhibits a high