Bromine monoxide is a binary inorganic compound of bromine and oxygen with the chemical formula BrO. A free radical, this compound is the simplest of many bromine oxides. The compound is capable of influencing atmospheric chemical processes. Naturally, BrO can be found in volcanic plumes. BrO is similar to the oxygen monofluoride, chlorine monoxide and iodine monoxide radicals.

The compound is very effective as a catalyst of the ozone destruction. The chemical reaction of BrO and chlorine dioxide (OClO) results in ozone depletion in the stratosphere.