Proton Conducting gel polymer electrolytes (GPEs) are taking much attention compared to liquid electrolytes for supercapacitor applications because of their physical properties, electrochemical stability and operation over broader temperature window. Among different GPEs PVA/acid blend electrolytes such as PVA/H2SO4, has drawn great attention in recent years. In this study, PVA-H2SO4-H3BO3 GPE was introduced for electric-double layer capacitor (EDLCs) application, in which electrospun free-standing carbon nanofibers are used as electrodes. Introduced PVA-H2SO4-H3BO3 GPE serves as both separator and the electrolyte in the supercapacitor. Symmetric Swagelok cells including GPEs were assembled via using two electrode arrangements and the electrochemical properties were searched. Electrochemical performance studies demonstrated that PVA-H2SO4-H3BO3 GPE had a maximum specific capacitance (Cs) of 134 F g(-1) and showed great capacitance retention (%100) after 1000 charge/discharge cycles. Furthermore, PVA-H2SO4-H(3)BO(3)GPE yielded an energy density of 67 Wh kg(-1) with a corresponding power density of 1000 W kg(-1) at a current density of 1 A g(-1). (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.