In this work a series of carbon adsorbents were prepared from a low-cost biomass residue, olive stones. Two different approaches were studied: activation with CO2 and heat treatment with gaseous ammonia. The results showed that both methods are suitable for the production of adsorbents with a high CO2 adsorption capacity, and their potential application in VSA or TSA systems for postcombustion CO2 capture. It was found that the presence of nitrogen functionalities enhances CO2 adsorption capacity, especially at low partial pressures. (C) 2009 Elsevier Ltd. All rights reserved.