5-Halo-3-ogaperfluoroalkanesulfonyl fluoride,[R_FCFXCF₂OCF₂CF₂SO₂F](1,2a,b～6a,b) were prepared from the reaction of higher homologs of fluoroolofin R_FCF=CF₂[R_F=CF₃,Cl(CF₂)2～4,H(CF₂)₄,n-C₃F₇O] with tetrafluoroethane sultone,potassium fluoride and halogen in diglyme.The effects of the structure of the fluoro-olefin and reaction temperature on the yields of the sulfonyl fluoride were discussed.When the sulfonyl fluorides,R_FCFXCF₂OCF₂CF₂SO₂F(5b,2b,8,9) were treated with cobaltio trifluoride,SO₂ was eliminated,and the fluoroalkanes R_FCFXCF₂OCF₂CF₂SO₂F(7,10-12) were obtained.By controlling the reaction conditions,once mole equivalent of SO₂ was lost in the oase of disulfonyl fluoride 13 to give the monosulfcnyl fluoride 14.