AbstractUnder appropriate conditions, the photolysis of iodoaromatic compounds yields derivatives of biphenyl and phenanthrene, as well as organometallic compounds. Ring closures of o‐terphenyls to triphenylenes and of benzanilides to phenanthridones are described. The formation of dehydrobenzene (benzyne) on photolysis of 1,2‐diiodobenzene in solution has been established. The photolysis of various substituted iodoaromatic compounds or of substances such as CH3I, ICN, ICH3, COOH, or RCCI, provides a general method for the generation of a large variety of free radicals in solution. The potential uses of photochemically initiated exchanges of iodine in ArI for131I, Li, D, Cl, or Br are