Amorphous MoS2 nanoflowers assembled by lamellar nanosheets have been successfully synthesized by a facile hydrothermal method. They were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and evaluated as electrochemical catalysts in the hydrogen evolution reaction (HER). Moreover, the effect of preparation temperature was also discussed. It was found that these catalysts exhibited excellent HER activity compared to commercial bulk MoS2 microparticles due to the special structure of nanoflowers assembled by nanosheets with few layers, exposing much more active sites and reducing intrinsic resistance. And the catalyst obtained at 220 degrees C showed the best activity with the largest exchange current density and the smallest Tafel slope of 52 mV dec(-1), which made it a promising HER electrocatalyst for practical applications. (C) 2014 Elsevier B.V. All rights reserved.