Electrochemical power sources that offer high energy and power densities and, can also withstand a harsh temperature range have become extremely desirable in applications ranging from civilian portable electronic devices to military weapons. In this report, we demonstrated a wide temperature withstanding supercapacitor which can be operated from 100°C to −40°C within a voltage window from −2V to 2V. The performance of the supercapacitor coin cells, assembled with nanostructured activated carbon fabric (ACF) as the electrode material and 1M tetraethylammonium tetrafluoroborate (TEABF4) in polypropylene carbonate (PC) solution as the electrolyte, was systematically studied within the set temperature window. The ACF supercapacitor yielded ideal rectangular shapes in cyclic voltammograms within 0–100°C with an average mass capacitance of 90Fg−1 and, 60Fg−1 at −25°C. The capacitance was still over 20Fg−1 at the extremely low temperature of −40°C. Another exciting feature of the ACF supercapacitors was that they resumed their room temperature capacitance when cooled from 100°C and defrosted from −40°C, demonstrating an excellent repeatability and stability. The charge–discharge behavior of the ACF supercapacitors showed long-cycle stability at extreme temperatures. These high electrochemical performances make this type of supercapacitors very promising in many practical applications.