To overcome the drawback of low photocatalytic efficiency brought by electron hole pairs recombination and narrow photo-response range, a novel g-C3N4/Cu2O composite photocatalyst was designed and prepared successfully. Compared with bare Cu2O and g-C3N4, the g-C3N4/Cu2O composite exhibited significantly enhanced photocatalytic activity for acid orange-II (AO-II) degradation under visible light irradiation. Based on energy band positions, the mechanism of enhanced visible-light photocatalytic activity was proposed. (C) 2014 Elsevier Ltd: All rights reserved.