Thermal desorption spectroscopy (TDS) allows for distinguishing among internal, external, and groove adsorption sites on carbon nanotubes (CNTs). Thus, TDS can be applied to study the effect of CNTs' crystal structure on adsorption kinetics. On clean CNTs, the binding energy for methanol increases with increasing CNT diameter, consistent with theoretical predictions. However, kinetics results can be obscured by rather subtle solvent (impurity) effects which are probe molecule specific. (C) 2009 Elsevier B.V. All rights reserved.