composite solid reagent consisting of lead(II) fluoride and a small amount of sodium bromide has been found to facilitate the fluorination of allylichalides in acetonitrile to afford a mixture of the corresponding and rearranged fluorides in the ratio of 1:1 to 1:2. Such allylic rearrangement is not observed when KF/18-crown-6 or tetrabutylammonium fluoride are employed.