A novel visible-light-active CdS@g-C3N4 photocatalyst was synthesized via a chemisorption method. This core@shell structure catalyst exhibited enhanced photocatalytic H-2 production activity under visible-light (lambda >= 420 nm) irradiation. The nano-sheet g-C3N4 was successfully coated on CdS nanoparticles with intimate contact. When the content of g-C3N4 in the hybridized composite is 3 wt. %, the hydrogen-production rate of the CdS g-C3N4 is 2.5 and 2.2 times faster than pure CdS and bulk g-C3N4, respectively. Superior stability was also observed in the cyclic runs. The improvement in stability and activity result from the ability of the pi-conjugated g-C3N4 material in transporting photo-induced holes. The core@shell structure promoted separation of the photo-generated electron-hole pair and accelerated the emigration speed of the hole from the valence band of CdS. This effect also results in a greatly improved amount of hydrogen production. The possible mechanism for the photocatalytic activity and stability of CdS g-C3N4 are tentatively proposed. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.