Highly active monolayer MoS2/reduced graphene oxide (ML-MoS2/RGO) catalysts have been fabricated with the assistance of cetyltrimethylammonium bromide via a solution route. The as-prepared catalysts are systematically investigated by X-ray diffraction, Raman spectra, field emission scanning electron microscopy and high-resolution transmission electron microscopy. Layer-depended catalytic performance of MoS2 active component has been demonstrated in the model hydrodesulfurization reaction of carbonyl sulfide. The ML-MoS2/RGO composites show superior catalytic activity compared with few layer MoS2/RGO (FL-MoS2/RGO) catalyst or bulk MoS2 with multilayer structure, which can be ascribed to more exposure of MoS2 active sites on monolayer MoS2 combined with high dispersion of monolayer MoS2 nanoparticles on RGO sheets. This work offers a facile strategy for the synthesis of monolayer MoS2 supported on RGO for efficient catalysis applications. (C) 2016 Elsevier B.V. All rights reserved.