Highly active, durable and inexpensive HER catalyst for electrochemical hydrogen evolution is a significant solution to cope with the energy crisis. Herein, self-assembled CoSe2 nanocrystals embedded into carbon nanowires (CoSe2@CNWs) have been synthesized by a facile hydrothermal reaction and subsequent selenylation process. Compared to bare CoSe2 NWs, the CoSe2@CNWs show outstanding performance of hydrogen evolution reaction (HER) with a small Tafel slope of 41.3 mV dec 1 and a low onset potential of similar to 130 mV vs RHE. Moreover, the CoSe2@CNWs also demonstrate good long-term stability in acidic electrolyte with a high current retention of 94.1% after 1500 cycles. The excellent HER performance of CoSe2@CNWs is attributed to the unique architecture constructed by CoSe2 nanocrystals embedded into highly conductive carbon nanowires, which guarantees rich active reaction sites and facilitates the charge transportation in HER process. (C) 2017 Elsevier Ltd. All rights reserved.