The cheap commercial activated carbon (AC) was improved through the secondary activation under steam in the presence of FeCl2 catalyst in the temperature range of 800-950℃ and its application in electric double layer capacitors (EDLCs) with organic electrolyte was studied. The re-activation of AC results in the increases in both specific capacitance and high rate capability of EDLCs. For AC treated under optimized conditions, its discharge specific capacitance increases up to 55.65 F/g, an increase of about 33% as compared to the original AC, and the high rate capability was increased significantly. The good performances of EDLC with improved AC were correlated to the increasing mesoporous ratio. The cheap commercial activated carbon (AC) was improved through the secondary activation under steam in the presence of FeCl2 catalyst in the temperature range of 800-950 ° C and its application in electric double layer capacitors (EDLCs) with organic electrolyte was studied. The re -activation of AC results in the increases in both specific capacitance and high rate capability of EDLCs. For AC treated under optimized conditions, its discharge specific capacitance increases up to 55.65 F / g, an increase of about 33% as compared to the original AC , and the high rate capability was increased significantly. The good performances of EDLC with improved AC were correlated to the increasing mesoporous ratio.