The reaction of hydrogen atoms with trifluoroethylene has been studied at room temperature by using the mercuryphotosensitizeddecomposition of hydrogen as the source of hydrogen atoms. Product analyses using gas chromatography and 1H and 19F NMR spectroscopy confirmed the 1,2-migration of a fluorine atom in the CH2F\dotCF2 radical produced by the addition of a hydrogen atom to trifluoroethylene.