A new visible absorption spectrum arising from a gaseous transient spe
cies in the bromine sensitized decomposition of ozone has been observe
d. The spectrum shows a series of absorption bands from 400-600 nm sup
erimposed on a continuum, with a maximum absorption near 505 nm and is
attributed to the symmetrical bromine oxide, OBrO, possibly formed fr
om the reaction of BrO with O-3. The implications for the partitioning
of BrOx in the atmosphere are briefly discussed.