a spectrophotometric method for the determination of Isoproturon and Metoxuron in technical and formulation grade samples based on the reaction with citric acid-acetic anhydride reagent has been developed. The absorption maxima of the coloured compounds so formed are 408 and 409 nm and the molar absorptivities are 1.69 X 10(2) and 1.13 X 10(2) L mol(-1) cm(-1) respectively. The reaction variables have been optimized and the reaction mechanism is discussed. The method is simple, convenient and successfully applied for the determination of Isoproturon and Metoxuron in technical and formulation grade samples. The percent relative standard deviation is found to be in the range 0.6-1.55 for Isoproturon and 1.24-1.90 for Metoxuron.