The present work finds a new method for the synthesis of nanoporous graphene and its applications in high energy density supercapacitor. The synthesis of nanoporous graphene by wet chemical method using Mg/Zn strip as a reducing agent has been reported by many researchers, but its application of supercapacitor is not yet reported. The nanoporous graphene exhibited variations in structure, morphology, and electrochemical properties as compared to chemical reduction by sodium borohydride. In contrast, the formation of nanoporous graphene using Mg/Zn, it's much faster than the chemical reduction by sodium borohydride. However, a significant improvement in the supercapacitor performance was observed upon Mg/Zn reduction method. In addition, the high electrical conductivity, improved higher surface area, better cyclability and typical electrochemical property enables one of the best high-rate performances studied for electrochemical supercapacitors: specific capacitance of 204 Fg(-1) obtained at 10 Ag-1 with capacitance retention of 95% after 20000 cycles of charge-discharge. (C) 2017 Elsevier B.V. All rights reserved.