Iodine monoxide is a binary inorganic compound of iodine and oxygen with the chemical formula IO•.

A free radical, this compound is the simplest of many iodine oxides.

[1][2][3] It is similar to the oxygen monofluoride, chlorine monoxide and bromine monoxide radicals.

Iodine monoxide can be obtained by the reaction between iodine and oxygen:[4] Iodine monoxide decomposes to its prime elements:[citation needed] Iodine monoxide reacts with nitric oxide:[5] Atmospheric iodine atoms (e.g. from iodomethane) can react with ozone to produce the iodine monoxide radical:[6][5] This process can contribute to ozone depletion.

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