Abstract: Carbon aerogels were prepared using a solgel process with resorcinol and formaldehyde as raw materials and sodium carbonate as catalyst, followed by ambient drying and carbonization. They were then activated by carbon dioxide. The activated materials were used as electrode materials of electric doublelayer capacitors and their electrochemical behavior was characterized by constant current chargedischarge experiments and cyclic voltammetry in an electrolyte of 6mol/L KOH aqueous solution. Results showed that the BET surface area and total pore volume of the aerogels were increased greatly by CO2 activation. When the carbon aerogel was activated by CO2 at 900℃ for 3h, its BET surface area increased from 633m2/g to 1271m2/g, and the corresponding specific capacitance increased from 81F/g to 172F/g at a current density of 1mA/cm2. When the current density was increased from 1 to 30mA/cm2, the specific capacitance of the activated sample decreased from 172 to 131F/g, indicating that the sample possessed an excellent power capability.