Activation of grape seeds char upon cyclic oxygen chemisorption-desorption permits a controlled development of porosity versus burn-off using air as a cheap activation agent. In this work the influence of chemisorption and desorption temperature and the number of cycles is investigated. A fast increase of BET surface area (S-BET) is obtained in the two first cycles; that increase becomes then lower although the S-BET continues increasing upon the successive cycles. Regarding the Dubinin-Astakhov surface area (S-DA) a slow increase was observed from cycle to cycle. The activation process led to the development of both micro and mesoporosity. Under the optimum conditions for surface area development, i.e. an oxidation temperature of 275 degrees C and desorption temperatures between 850 and 950 degrees C, values of 1129-1256 and 1339-1219 m(2)/g were obtained for S-BET and S-DA, respectively. Porosity was found to increase mainly during the desorption stage, although chemisorption also led to some surface area development. SEM characterization showed that the activated carbon maintained the granular morphology of the seeds even after 10 cycles showing the egg-shell structure of the precursor with longer and deeper cracks at the outer surface. The activated carbons showed a good mechanical strength during attrition tests. (C) 2013 Elsevier B.V. All rights reserved.