In this work, graphene oxide-cuprous oxide (GO-Cu2O) composite films were grown on fluorine-doped tin oxide substrates by electrochemical deposition. We investigated the effects of the annealing temperature on the morphological, structural, optical and photoelectrochemical (PEC) properties of GO-Cu2O composite films. As a result, our work shows that while GO-Cu2O composite films exhibit the highest XRD (111) peak intensity at 300 degrees C sample, the highest photocurrent density value obtained was -4.75 mA/cm(2) at 200 degrees C sample (using 0.17 V versus a reversible hydrogen electrode (RHE)). In addition, a reduction reaction at 300 degrees C sample was observed using XPS analysis from the shift in the O1s peak in addition to a weaker O1s peak intensity. (C) 2015 Elsevier B.V. All rights reserved.