The catalytic activity of molybdenum sulfide (MoS2) for hydrogen evolution reaction (HER) strongly depends on the number of exposed active edges of MoS2 nanosheets. Making single or few-layer MoS2 nanosheets vertically stand on a substrate is a very effective way to maximally expose the edge sites of MoS2 nanosheets. Vertically standing single or few-layer MoS2 nanosheets on porous TiO2 nanofibers (TiO2@MoS2) are successfully prepared via a simple hydrothermal reaction. Due to plenty of pores in the electrospun TiO2 nanofibers, the MoS2 nanosheets vertically grow from the inside to the outside, and the growth mode of the MoS2 nanosheets rooting into the TiO2 nanofibers endows not only intimate contact between TiO2 and MoS2 for fast electrons transfer but also high structural stability of TiO2@MoS2 heterostructure. The vertical orientation of MoS2 nanosheets enables the active edge sites of MoS2 to be maximally exposed. Without using Pt cocatalyst, the TiO2@MoS2 heterostructure achieves high photocatalytic hydrogen production rates of 1.68 or 0.49 mmol h(-1) g(-1) under UV-vis or visible light illumination, respectively. This high photocatalytic activity arises from the positive synergetic effect between the MoS2 and TiO2 components in this novel heterostructure. In addition, the TiO2@MoS2 heterostructure exhibits a high durability as evidenced by the invariable hydrogen production rate after continuous illumination over 30 h. The work advances the development of highly efficient molybdenum sulfide-based HER catalysts. (C) 2014 Elsevier B.V. All rights reserved.