Two types of fluoro-functionalizations mediated by reactive chalcogen reagents have been summarized. The first is a generation of benzeneselenenyl fluoride and its electrophilic reactions with alkenes, electron-deficient alkenes, isonitriles and α-diazocarbonyl compounds. The second is a single electron transfer (SET) reaction of benzene chalcogenolates to perfluoroalkyl halides such as trifluoromethyl bromide, dibromodifluoromethane, bromodifluoroacetates etc., where perfluorinated alkyl radicals generated in the SET reaction undergo addition to alkenes and alkynes to give perfluoroalkyl-chalcogenated molecules.