Activation of waste tire char upon cyclic oxygen chemisorption-desorption permits a controlled development of porosity versus burnoff using air as feed gas for the activation process. A slow but monotonical increase of BET surface area is obtained from cycle to cycle. Initially the process led to the development of mesoporosity without generating micropores and then the micropore volume is increased whereas a decrease of narrow mesopore (20-80 nm) volume is observed, probably as a consequence of mesopore widening. Although the S-BET reaches relatively low values (below 250 m(2)/g) even after 15 cycles, this surface development is associated with low burnoff values (around 22% for indicated BET surface area) and corresponds in an important percentage (up to about 50%) to external (nonmicropore) area. Temperatures around 210 and 550 degrees C for chemisorption and desorption, respectively, have been found as optimum for the purpose of preparing mesoporous carbons which can be interesting candidates as catalytic supports for liquid phase applications.