The potential to form BrO3−as a byproduct during ozone treatment of raw water containing bromide ion is a major concern for utilities planning to use ozone. The proposed BrO3−Maximum Contaminant Level (MCL) of 10 μg/L in the USA has been established largely by using ion chromatography. A spectrophotometric method based on the oxidation of chlorpromazine in the presence of BrO3−has been developed. The method detection limit (MDL) in reagent water is 0.8 μg/L BrO3−The procedure has an operating range of 1 to 40 μg/L BrO3. The precision of the method is calculated to be better than 2.5% with an accuracy within ± 1 μg/L BrO3−. Details of the method are presented along with data gathered by ion chromatography using borate and carbonate eluants; chlorpromazine post column studies; and low level capillary electrophoresis studies.