Three different modes of fluorine chemisorption at the surface of SWNTs have been unambiguously evidenced and their respective amounts quantified, using selective thermal desorption. The C-F bonds formed in this case seem to correspond to the three kinds of bonds previously identified in the different forms of graphite fluorides. The overall bonding scheme in a fluorotube relates to the fluorination temperature used and always consists of a mixture of several C-F bond types in different proportions, making one essential difference with fluorographites. Metastability or different fluorine locations might be at the origin of the phenomenon. (c) 2007 Elsevier B.V. All rights reserved.