The reaction of multi-walled carbon nanotubes (MWCNT) with xenon difluoride has been studied and compared with the results from experiments with elemental fluorine. A low level fluorination of MWCNTs was achieved at ambient temperature under the influence of light. The outer shells of the nanotubes were converted into a fluorine containing coating that did not significantly affect the electrical conductivity. Fluorination with xenon difluoride was found to be partly irreversible, contrary to previous findings. (C) 2004 Elsevier B.V. All rights reserved.