Molybdenum, for the first time, was used as a new type of sulfur host for lithium-sulfur batteries and exhibited outstanding electrochemical performance, even over traditional porous carbon hosts. A Mo-S composite, with 80 wt% sulfur loading, delivered reversible capacities of 1003 mAh g−1 after 130 cycles at 0.1 C, and 786 mAh g−1 after 100 cycles at 5.0 C. Further analysis using in situ X-ray diffraction, cyclic voltammetry, and density functional theory calculations demonstrated that the Mo surface can not only effectively trap polysulfides, but also catalytically decompose polysulfides and Li2S.