To ensure compliance with current and expected disinfection byproduct regulations, the Metropolitan Water District of Southern California researched ways to reduce ozonation pH through the use of sulfuric acid to minimize the formation of bromate. Research was carried out at a demonstration plant. The benchmark system was defined as the medium-frequency generator producing a 6-percent gas-phase ozone concentration, coupled with the over/under contactor operated at a 12-min theoretical hydraulic residence time. The benchmark system required less applied ozone to achieve similar disinfection and formed less bromate than other systems tested (air-fed, eductor). Ozonation of water containing high levels of bromide at ambient pH generally produced bromate concentrations greater than 10 ug/L and never less than 5ug/L. Reducing the pH of ozonation to 6.0 generally resulted in bromate levels below 5 ug/L, even with bromide concentrations up to 0.5 mg/L. Waters containing bromide levels above 0.2 mg/L will probably require pH adjustment prior to ozonation to minimize bromate formation. Ozonation at a reduced pH required a lower applied ozone dosage to achieve disinfection (CT) requirements, which may defray a portion of the acid addition costs.