DHydrogen storage mechanism and hydrogen storage capacity are the great challenges for the development of hydrogen energy technology. Besides the better catalytic properties, it is crucial to search for suitable material that provides enough space to store H-2 molecule. Similar to graphene, MoS2 with S-S layered structure opens up a new way to improve the hydrogen storage capacity. By using the first-principles calculations, in this work, we investigate the hydrogen diffusion mechanism, hydrogenation process and hydrogen storage capacity of MoS2 with S-S interlayer. We find that hydrogen prefers to diffuse into S-S interlayer along the interstitial site (path: IT-IT). H-2 molecule is a stable in S-S interlayer because the charge interaction of H-H atoms is stronger than that of H-S atoms. Finally, we predict that MoS2 with S-S layered-by-layered stacking can effectively improve the hydrogen storage capacity. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.