Exploiting active, stable, and cost-efficient cocatalysts is crucial to enhance the photocatalytic performance of semiconductor-based photocatalysts for H-2 evolution from water splitting. Herein, we report on using vanadium diboride (VB2) as an efficient cocatalyst to enhance the photocatalytic H-2 evolution performance of CdS nanoparticles under visible light irradiation (lambda >= 420 nm). The CdS/VB2 composites prepared by a facile solution-mixing method exhibit much improved H-2 evolution activities in 10 vol% lactic acid (LA) solution relative to pristine CdS. The most efficient CdS/VB2 composite with 20 wt% VB2 (CB20) exhibits a H-2 evolution rate as high as 12.1 mmol h(-1) g(-1), which is about 11 times higher than that of CdS alone (1.1 mmol h(-1 )g(-1)). Moreover, the highest apparent quantum efficiency (AQE) of 4.4% is recorded on CB20 at 420 nm. The improved photocatalytic activity of CdS/VB2 composite can be attributed to the excellent cocatalytic effect of VB2, which can not only enhance the charge separation on CdS but also accelerate the H-2 evolution kinetics. This work demonstrates the great potential of using transition metal brodies (TMBs) as efficient cocatalysts for developing noble-metal-free and stable photocatalysts for solar photocatalytic H-2 evolution. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.