Monodisperse activated carbon spheres (ACSs) with high specific Brunauer-Emmett-Teller (BET) surface area were prepared from colloidal carbon spheres (CCSs) by steam activation. The effects of the gasification time on the surface properties of ACSs were investigated. The results exhibited that ACSs have a high specific surface area (2870 m(2) g(-1)) and a large total pore volume (1.456 cm(3) g(-1)). The electrochemical measurements were conducted by cyclic voltammetry. The results demonstrated that the specific capacitance of electrode material reaches 229F g(-1) at a sweep rate of 2mVs(-1).