Effects of electron donors on photocatalytic production of H-2 and hydrocarbons over Cu2O photocatalyst have been systematically investigated in this paper. The cubic Cu2O has been synthesized by reduction precipitation method and further characterized by XRD, SEM and UV-vis DRS. Short chain fatty acids (SCFAs) including acetic acids, propionic acids and butyric acids, main by-products produced during dark H-2 fermentation, have been chosen as typical electron donors. Experimental results showed that distributions of gaseous products during photocatalytic water-splitting process were greatly influenced by individual and mixed SCFAs. Using three mixed SCFAs as electron donors, the overall carbon recoveries obtained in this study are in range of 86.11-95.36%. The AQEs in our photo catalytic system are changed from 4.88% to 8.94%. The AECEs in our photocatalytic system are varied from 4.46% to 10.48%. Based on our experimental results, a novel route for renewable energy generation from organic wastes or wastewater can be established by coupling dark H-2 fermentation with photocatalytic system. According to distributions of gaseous products and known intermediates, a possible mechanism about photocatalytic decomposition of SCFAs for production of H-2 and hydrocarbons has been proposed and analyzed as well. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.