A simple method for activating polyaniline (PANI) using NH3 for the synthesis of high performance electrode materials in supercapacitors is described. The PANI is activated at various temperatures (750–1050°C) with a mixed stream of NH3 and N2. Because of the corrosive properties of NH3, the surface area of PANI (46.6m2 g−1) is significantly increased up to 1719.8m2 g−1. Large amounts of surface nitrogen functional groups are maintained in pyrrolic and pyridinic states, even after a heat treatment, which is favorable for pseudocapacitor reactions. As evidenced by electrochemical analysis, NH3 activated PANI exhibits a high specific capacitance (174.8Fg−1) and fast charging/discharging characteristics due to its high specific surface area and desirable surface functional groups. Results suggest that it has considerable potential for use in application to PANI based composites as a high performance electrode material in supercapacitors.