The instant invention relates to producing perhalofluorobutanes and perhalofluorohexanes, more particularly it relates to their production by utilizing tetrafluoroethylene (hereinafter referred to as “TFE”) and chlorotrifluoro-ethylene (hereinafter referred to as “CTFE”) with selected perhalofluoroethanes containing 2 to 4 nonfluorine halogen and 2 to 4 fluorine substituents in the presence of a polyvalent metal halide such as an aluminum chloride or chlorofluoride as catalyst.