Mediator-enhanced polymer electrolyte supercapacitors (MEPESCs) were fabricated using poly(ethylene oxide)/LiClO4 as the polymer electrolyte in the porous activated carbon electrodes and a Nafion 117 membrane as a separator. NaI and I-2 were added into the polymer electrolyte as mediators to increase both the conductivity of the polymer electrolyte and the specific charge of the MEPESC. Based on the cyclic voltammetry and galvanostatic charge/discharge measurement tests, the total specific charges of the supercapacitor without and with redox mediators are 45 and 210 C g(-1) within a voltage window of 0.0-1.0 V, respectively, showing a significant enhancement effect for the mediators. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3526094] All rights reserved.