Walnut Shell-derived hierarchical porous carbon has been successfully synthesized by the efficient KOH activation process. The hierarchical porous carbon material activated at 600 degrees C, has the specific micropore area of 1037.31 m(2) g(-1) and micropore volume of 0.51 cm(3) g(-1), which leads to have electrochemical performances of the hydrogen evolution reaction (HER) and supercapacitors. Specifically, as the hydrogen evolution reaction electrocatalyst, the walnut shell-derived carbon material activated at 600 degrees C exhibits a lower onset potential of 6.00 mV, a smaller Tafel slope of 69.76 mV dec(-1) and outstanding stability above long-term cycling. As a supercapacitor electrode material, the sample possesses specific capacitance of 262.74 F g(-2) at 0.5 A g(-1), the remarkable rate capability of 224.60 F g(-1) at even 10 A g(-1) and good long-term stability. A symmetric supercapacitor shows the highly energy density of 7.97 Wh kg(-1) at a power density of 180.80 W kg(-1). This novel and low-cost biomass material is very promising for the electrocatalytic water splitting and supercapacitors. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.