Multiwall carbon nanoparticles from the inner part of a deposit grown onto a cathode in an are-discharge condition were fluorinated at room temperature using volatile fluoride BrF3. The sample produced was characterized by means of X-ray diffraction (XRD), infrared (IR) and X-ray photoelectron spectroscopy (XPS). These methods point to the presence of covalent C-F bonds in the sample with retention of the sp(2)-hybridizated carbon atoms composing the cage tubular or quasi-spherical shells. Transmission electron microscopy (TEM) indicated a decrease of cage nanoparticles in the fluorinated material relative to the pristine sample that may be connected with unrolling the nanotubes during fluorination.