Rationally designing noble-metal-free metallic cocatalysts modified graphitic carbon nitride (g-C3N4) as heterostructured photocatalysts is an efficient strategy for enhancing photocatalytic hydrogen (H-2) evolution. Herein, uniform molybdenum diselenide (MoSe2) nanoparticles were synthesized through a simple solvothermal approach, and the MoSe(2)nanoparticles anchoredg-C(3)N(4)nanosheets were subsequently prepared by a solution-phase strategy. The resulting MoSe2/g-C(3)N(4)nanocomposite displayed good performance toward visible-light photocatalytic H(2)production. The optimal amount of MoSe(2)nanoparticles was 7% of composite by weight, displaying the highest H(2)production rate of 287.3 mu mol h(-1)g(-1). The excellent photocatalytic performance of the MoSe2/g-C(3)N(4)hybrids was ascribed to the introduction of MoSe(2)nanoparticles, which facilitated the charge separation and dramatically promoted the photoelectron transport. The insight into the charge transfer through the interface between MoSe(2)nanoparticles andg-C(3)N(4)nanosheets was revealed by photoluminescence spectra, electrochemical and photoelectrochemical experiments. This work provides solid evidence that MoSe(2)nanoparticles can be a promising cocatalyst loadedg-C(3)N(4)for enhanced photocatalytic performance. [GRAPHICS] .