Cypress charcoals, which were prepared under super-heated steam and had a relatively large amount of mesopores, were used in electric double layer capacitors (EDLCs) in 1 mol/L H 2 SO 4 electrolyte. The gravimetric capacitance of cypress charcoals was about 190 F/g at a current density of 50 mA/g (C 50 ) and 140 F/g at 1000 mA/g (C 1000 ) and the performance rating defined by C 1000 /C 50 was about 0.72. The capacitance observed was explained by the contributions from the surfaces from the micropores and the larger pores. By loading minute NiO particles through a simple impregnating process, the capacitance of the loaded charcoals was enhanced by about 13% in gravimetric capacitance and by about 27% in volumetric capacitance and the performance rating was kept the same.