Activated Carbons were prepared from esparto grass (Stipa tenacissima) by activation with different amounts of KOH and different temperatures of pyrolysis. The study of carbonization was carried out by thermal analysis (DSC, Tg, DTg and simultaneous Mass spectroscopy). Moreover, the characterization of surface carbons was performed by means of measurement of surface area, by BET method (S-BET), the micro and mesopore area, by Dubinin-Radushkevich (S-mic and S-ext), the pore size distribution, by DFT and the surface charge distribution, by potential Zeta and Mass Titration. Probes of adsorption with anionic surfactant were carried out. These results suggest that the fundamental factor over adsorption was the development of mesoporosity in carbons activated at greats ratios of KOH impregnation. (C) 2001 Elsevier Science B.V. All rights reserved.