AbstractUpon ultraviolet irradiation azobenzene and decafluoroazobenzene in cyclohexane and diethyl ether solutions decompose into phenylazo, phenylazomethylene and aniline radicals. The major products formed in cyclohexane solution are N‐cyclohexylaniline, N‐cyclohexylpentafluoroaniline, phenylazocyclohexane, pentafluorophenyl‐azocyclohexane, 1‐phenyl‐2‐cyclohexylhydrazine and 1‐pentafluoro‐2‐cyclohexyl hydrazine. In diethyl ether solution the products are N‐polymethylene phenylhydrazine, N‐polymethylene pentafluorophenyl hydrazine, phenylhydrazine cyclohexane, pentafluorophenyl hydrazine cyclohexane and phenylazo‐N‐polymethylene. Minor products are also formed from the photosensitisation of solvent molecules. The primary and secondary reactions of the azobenzenes which lead to these products are discussed.