Adsorption of CO2 on purified single-walled carbon nanotubes (SWNTs) has been studied in the temperature range of 0-200 degreesC and found to be mainly a physisorption process. The SWNTs adsorb nearly twice the volume of CO, compared to activated carbon. The experimental results yield a CO, heat of adsorption of 2303 J/mol (0.024 eV) in SWNTs. Our computational study yields a similar binding energy and shows that the CO2 is physisorbed side-on to the nanotube. (C) 2003 Elsevier B.V. All rights reserved.