High surface area activated carbon was prepared from Enteromorpha prolifra (E. prolifra) using few activating agents through a dry-grind strategy. The influences of pyrolysis conditions, including activating agent/char ratio, activation temperature and activation time, on specific surface area, micropore ratio and mean pore size of the obtained carbons were investigated by response surface methodology (RSM). Moreover, the relationships of micro/mesopore ratio with the surface area and mean pore size were also discussed. The optimized parameters were activating agent/char ratio of 1.1 (KOH/char), activation temperature of 850 degrees C and activation time of 60 min. Activated carbon prepared under optimum conditions possessed high surface area of 3038 m(2) g(-1) and large total pore volume of 2.285 cm(3) g(-1). The obtained carbon was used as an electrode material. The carbon electrode exhibited a high specific capacitance of 230 F g(-1) at a current density of 0.5 A g(-1) with a good capacitance retention of 86.96% at a high current density of 5.0 A g(-1) in 6 M KOH electrolyte. (C) 2015 Elsevier B.V. All rights reserved.