In present study, photocatalytic production of alkanes and hydrogen gas from butyric acid solution over Cu2O/Bi2WO6 composites has been investigated under UV irradiation. The Cu2O/Bi2WO6 heterojunction composites were synthesized by a two-step method, first by a hydrothermal method, and then by a simple reduction precipitation method. The as prepared samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), ultraviolet visible diffuse reflection spectroscopy (DRS) and photoluminescence spectroscopy (PL). In Cu2O/Bi2WO6 composites, the larger spherical Cu2O were covered by smaller Bi2WO6 nanosheets. The 24.36 wt%Cu2O/Bi2WO6 composite showed the highest photo catalytic activity for production of alkanes and hydrogen gas. The enhancement in photocatalytic activity can be ascribed to increment in light absorption and effective inhibition of recombination of photogenerated carriers at the heterostructure interface. Based on distributions of gaseous products and intermediates in liquid, a possible mechanism for photocatalytic decomposition of butyric acid over Cu2O/Bi2WO6 composites is proposed. Our results provide a method for pollutants removal with simultaneous production of alkanes and hydrogen. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.