Synthesizing and designing of the hydrogen evolution reaction (HER) electrode composed of earthabundance elements is the current research topics. Among the many discovered catalysts, cobalt disulfide has outstanding performance for HER due to its catalytic activity cobalt sites. Here, phosphorusdoped cobalt disulfide (P doped CoS2) samples are successfully synthesized via simple one-step hydrothermal method. By using them as the electrocatalysts, the most efficient electrode we obtained shows the excellent electrocatalytic activity, with low overpotential of 53 mV to achieve a 10 mA/cm(2) current density, a small Tafel slope of 57 mV/dec and a high stability after 10000 cycles. First-principle calculations results indicate that phosphorus dopants could improve the electrocatalytic activity of hydrogen evolution by lowing the free energy for atomic hydrogen adsorption (Delta G(H)*) at the Co sites. Moreover, the metallic P doped CoS2 could promote electron transfer and offers faster HER kinetics, thereby leading to better HER activity. This finding demonstrates an effective way to synthesis nonmetal doped CoS2 catalysts via one-step hydrothermal method and further improve the HER performance of CoS2 under the guidance of theoretical calculations. (C) 2017 Elsevier Ltd. All rights reserved.