Electron energy loss spectroscopy is used to record the vibrational spectra of CF(x) (x = 2 and 3) groups adsorbed on Pt(111). CF3 groups are produced from either the thermal decomposition of adsorbed CF3I or broadband photolysis of adsorbed CF3Br. The angular profile of the loss peak intensities indicates that adsorbed CF3 groups retain the gas-phase C3v symmetry. CF3 is stable on the surface until T approximately 450 K; heating to higher temperatures results in the decomposition of CF3 to yield adsorbed CF2.