WS2 nanosheets (WS2 NSs) as electrocatalysts for hydrogen evolution reaction (HER) have been prepared based on liquid exfoliation in dimethyl-formamide (DMF) via a direct dispersion and ultrasonication method. X-ray diffraction (XRD) shows the decreasing crystalline of the exfoliated WS2 (E-WS2). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that the as prepared E-WS2 consists of a few two-dimensional nanosheets, with large wrinkles on the surface. Electrochemical measurements show an excellent activity and stability of the E-WS2, with a low overpotential of 80 mV and high current density (10 mA cm(-2), at eta = 205 mV), which indicates that through the process of exfoliation in DMF, both the dispersion and the amount of active sites have been improved greatly. Therefore, DMF is a promising alternative for exfoliating two-dimensional nanomaterials for highly efficient HER electrocatalysts. (C) 2015 Elsevier B.V. All rights reserved.