We show that thermal desorption kinetics clearly resolve adsorbates bound in different sites on single walled carbon nanotube bundles. The molecules n-C9H2O and CCl4 were compared and it was found that the nanotube internal sites exhibited the highest desorption temperature, whereas external groove sites exhibited the next highest desorption temperature for both molecules. When n-C9H2O and CCl4 coadsorb the more strongly bound n-C9H2O quantitatively displaces CCl4 from internal sites to groove sites. Molecular shape governs the capacity of the different sites for the two molecules. (c) 2005 Elsevier B.V. All rights reserved.