The use of nanostructured composites as catalyst supports is a promising route to prepare catalysts with high selectivity and productivity. In this work, reduced graphene oxide-TiO2 (rGP-x) composites with a variation of reduced graphene oxide (rGO) content were synthesized by hydrothermal method. Pd/rGP-x catalysts were prepared in incipient-wetness impregnation method for the direct synthesis of H2O2 from H-2 and O-2. The morphology and electronic properties of catalysts were investigated by XPS, TEM, and Raman spectroscopy. The ratio of Pd2+/Pd-0 and the hydrophobicity of the catalysts were increased with the rising content of rGO. As the amount of rGO in the catalysts varied in the range of 0.025wt%-2wt%, the selectivity of H2O2 exhibited a tendency of increasing firstly and then decreasing from 0.1 wt% to 2 wt%. It indicates that good catalytic performance for H2O2 synthesis can be achieved only when appropriate amount of rGO is introduced. The H2O2 selectivity and productivity of Pd/rGP-0.025 both improved remarkably compared with Pd/P25. This enhancement originated from the combined effects of the proper ratio of Pd2+/Pd-0 and hydrophobicity of the catalyst. (C) 2017 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.