The halofluorination reaction of a variety of alkenes by using tetrabutylammonium bifluoride (TBABF) in the presence of N-halosuccinimide is described. This process occurs stereospecifically to afford anti addition producta, and with unsymmetrical olefins a marked Markovnikov-type regioselectivity is observed. In some cases, formation of a remarkable amount of the corresponding dihalo derivatives was found, but this undesirable side reaction can be avoided by using N-iodosuccinimide (NIS) as halogenating agent. If N-bromosuccinimide (NBS) or N-chlorosuccinimide (NCS) is utilized, these dihalo compounds can be easily removed from the halofluorinated compounds by simple column chromatography on silica gel. A mechanism for this side reaction is postulated.