Pd nanoparticles modified MoS2 nanoflowers assembled by lamellar nanosheets have been successfully synthesized by a facile hydrothermal method. They were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM, Nanoscope III), X-ray photoelectron spectroscopy (XPS), and evaluated as electrochemical catalysts for hydrogen evolution reaction (HER). It was found that Pd modified MoS2 (MoS2-Pd) without calcinated treatment exhibited high HER activity. The HER activity of this catalyst can be improved after visible-light irradiation. As a novel HER catalyst, the MoS2 Pd under illumination exhibited the best activity with the highest TOF value (0.013 s(-1)) and the lowest Tafel slope (39 mV dec(-1)). The results indicate that noble metal Pd plays an important role in promoting the HER activity. The increasing creation of electrons by visible-light irradiation is favorable for the electrochemical hydrogen adsorption reaction, which leads to more hydrogen formation. This work demonstrates the feasibility of increasing HER activity of MoS2-based catalysts by combining MoS2 with Pd noble metal nanoparticles. (C) 2015 Elsevier B.V. All rights reserved.