Abstract: Ascries of ortho-n-alkyl iodosobenzenes were synthesized from the corresponding n-alkyl iodobenzenes. Under the same conditions,it was found that with increasing in the carbon chain length of n-alkyl group, the formation of the corresponding ortho-n-alkyl iodosobenzene became more difficult and their stability decreased accordingly. Attempts for synthesizing ortho-n-alkyl iodosobenzene with carbon atoms more than five in the n-alkyl group were not successful. The structures of some ortho-n-alkyl iodosobenzenes were analyzed by ir and nmr spectra. The steric effect of the long chain n-alkyl groups in the formation of more stable polybridged structure was discussed.