In this work, high efficient non-noble metal cobalt cocatalysts implanted on the surface of graphene (G) by one-step photoreduction and in-situ chemical deposition methods for hydrogen evolution were reported. XRD and TEM characterizations showed that the Co and CoS nanoparticles were deposited on the graphene surface as Co/G and CoSx/G composites. CoSx/G and Co/G nanohybrids exhibited high photocatalytic activities for hydrogen evolution sensitized by Eosin Y (EY). The amounts of H-2 evolution reached 708.5 and 675.5 mu mol over the EY-sensitized CoSx/G and Co/G nanohybrids irradiated under visible light with wavelength longer than 420 nm in 3 h respectively. The apparent quantum efficiency (AQE) of 8.71% over EY-Co/G was accomplished under 520 nm illumination. The fluorescence results indicated that the lifetime of excited electron was remarkably increased. Graphene might promote the photogenerated electrons transfer from excited dye to the hydrogen evolution active sites such as Co or CoSx, and consequently enhance photocatalytic hydrogen evolution efficiency. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.