Abstract: A novel process is described for reacting a perfluoroalkyl iodide with an olefinic compound, which comprises carrying out a free-radical addition reaction of the perfluoroalkyl iodide to the olefin in the presence of azoic or peroxy initiator and a water-soluble salt selected from the group consisting of sulfites, bisulfites, metabisulfites and dithionites. The adducts are obtained in high yield and purity and are useful for the preparation of oil- and water repellent products for use on paper, textiles, metal, wood and the like, or as precursors for fluorinated surfactants.