A supercapacitor utilize a novel redox-mediated gel polymer (PVA-KOH-PPD) as electrolyte and separator, and activated carbon as electrodes is assembled. The PVA-KOH-PPD gel polymer as potential electrolyte for supercapacitor is investigated by cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy techniques. It is found that the supercapacitor exhibits high ionic conductivity (25 mS cm(-1)), large electrode specific capacitance (611 F g(-1)) and high energy density (82.56 Wh kg(-1)). The high performance is attributed to the addition of quick redox reactions at the electrolyte vertical bar electrode interface as PPD undergoes a two-proton/two-electron reduction and oxidation during cycling. Furthermore, the supercapacitor with PVA-KOH-PPD gel polymer shows excellent charge-discharge stability, after 1000 charge-discharge cycles, the supercapacitor still retains a high electrode specific capacitance of 470 F g(-1). It is believed that the idea using redox mediator has a good prospect for improving the performances of supercapacitors. (C) 2014 Elsevier Ltd. All rights reserved.