Disinfection of drinking water is usually carried out by chlorination. This is a well-known and effective technology which has many advantages. However, during this process dangerous by-products such as trihalomethanes, as well as chlorate and chlorite are formed. The disinfection of bromide-containing source waters with ozone results in the production of bromate ions (BrO3 -), which are formed as a result of a series of complex reactions between ozone and bromide ions present in water. Bromates are possible human carcinogens. For these reasons trace analysis of bromate and other oxyhalides by-products in waters has received considerable attention in recent years. This article describes the determination of bromate in drinking water by IC with post column derivatisation using NaBr/NaNO2 and UV detection. The direct method allows the determination of bromate at low ěg/dm3 levels and sample pretreatment is not necessary.