Aim To study the determination of trace bromide by the method of catalytic kinetic determination. Methods Spectrophotometry was used to study the optimum conditions influencing the rate of the oxidation of sodium diphenylamine sulphonic acidsalt by potassium bromate. Results A new spectrophotometric method with catalyst for the determination of trace Br - has been developed. The method is based on the inhibitory effect of Br - on the oxidation of sodium diphenylamine sulphonic acidsalt by potassium bromate in a solution of diluted H 3PO 4. Conclusion This method behaves with high sensitivity and high selectivity. The linear range of determination is (0.5-5.6) μg/mL for bromine ion. The method has been used to determine solution product of CuBr with satisfactory results.