Five samples of ordered mesoporous silica SBA-15 were synthesized. Its pore size was in the range 5-9 nm, and the specific surface area was in the range 500-900 m(2)/g, which was controlled by the temperature and time of aging on crystallization. Adsorption isotherms Of CO2, CH4 and N-2 on the samples were collected at 298 K, and the adsorption rates of the gases were also compared for different pressures. It was concluded that SBA-15 with the textural property studied was a good adsorbent for the separation of carbon dioxide from its mixture with methane and nitrogen. (c) 2005 Elsevier B.V. All rights reserved.