Activated carbon aerogels were obtained from the CO2 activation of carbon aerogels. The adsorption isotherms of nitrogen on activated carbon aerogels at 77 K were measured and analyzed by the high-resolution as plot to evaluate their porosities. The alpha(s) plot showed an upward deviation from linearity below alpha(s) = 0.5, suggesting that the presence of micropores becomes more predominant with the extent of the activation. Activation increased noticeably the pore volume and the surface area (the maximum value : 2600 m(2) . g(-1)) without change of the basic network structure of primary particles. Activated carbon aerogels had a bimodal pore size distribution of uniform micropores and mesopores.