The three-dimensional (3D) reduced graphene oxide/carbon nanotube nanocomposites (rGO/CNTs nanocomposites) and reduced graphene oxide nanocomposites (rGO nanocomposites) were anchored with amorphous MoSx, forming the MoSx-rGO/CNTs and MoSx-rGO nanocomposites. Their hydrogen evolution reaction (HER) activities were intensively evaluated. Results indicated that the rGO/CNTs nanocomposite provided more sites for the amorphous MoSx as compared with that of CNTs nanocomposite. Raman spectra of MoSx-rGO and MoSx-rGO/CNTs nanocomposites confirmed the amorphous state of MoSx in all MoSx anchored nanocomposites. TEM and SEM morphology indicated that the amorphous MoSx was well-dispersed on the rGO/CNTs and rGO nanocomposites. The amorphous MoSx nanoparticles in MoSx-rGO/CNTs and MoSx-rGO nanocomposites could provide more S atoms at their edges, and therefore greatly improve the HER activity. HER performances indicated that the rGO/CNTs and rGO nanocomposites anchored with crystalline MoS2 exhibited poor HER performance. In contrast, MoSx-rGO/CNTs and MoSx-rGO nanocomposites anchored with a small amount of MoSx exhibited the excellent HER activity (179 mV of overpotential at 10mA cm(-2)). Results also indicated that the HER activities of the MoSx-@rGO nanocomposites were a bit smaller than those of MoSx-rGO/CNTs nanocomposites. The CNTs in the rGO/CNTs nanocomposites would improve the intimate electrolyte/electrode contact and promote the high-rate charge transfer, which further strengthened their electrocatalytic hydrogen evolution performances. (c) 2018 Elsevier Ltd. All rights reserved.