A scalable, selective, and operationally easy iodotrifluoromethylation of a wide range of alkenes and alkynes by using two simple and safe solids, sodium trifluoromethanesulfinate and iodine pentoxide, in aqueous medium has been developed. Mechanistic studies confirm that free-radical processes are involved in this system since the key radical intermediates such as CF(3) and β-CF(3) alkyl radicals have been clearly detected by spin trapping and electron spin resonance.