A process for the addition of perfluoroalkyl iodides of the formula ZCn F2n I, where Z represents F or I, n is an integer of 4 - 18, said iodides are liquid at reaction temperature, to non-halogenated olefins or non-halogenated acetylenes which are gaseous at the employed reaction temperature, which comprises bubbling said olefin or acetylene into said liquid iodide, in the presence of a free-radi