A capillary zone electrophoresis (CZE) system for determining haloacetic acids in water was optimized with indirect photometric detection. Two different carrier electrolytes, potassium hydrogenphthalate and sodium 2,6-naphthalenedicarboxylate, were evaluated in terms of sensitivity and two different electroosmotic flow modifiers, tetradecyltrimethylammonium bromide and hexadecyltrimethylammonium bromide, were tested. Parameters such as electrolyte concentration and pH, and the concentration of the electroosmotic flow modifiers, which affect the CZE separations, were investigated. The method was used to determine haloacetic acids in chlorine tap water using the liquid-liquid extraction process.