The flow injection speciation of manganese in aqueous solution using a spectrophotometry method of detection is presented. Manganese (VII) can be determined spectrophotometrically at 308 nm after the reaction with Sym-diphenycarbazide in buffered at pH=3.05 with phosphate. Under the optimized conditions, total manganese concentration can also be determined after oxidation of Mn2+ to MnO4- and then Mn2+ concentration can be calculated from the difference. The linear range of determination is 0.047-4.50 mg/l with a 3sigma detection limit of 31 mug/l. The proposed method is applied to the determination of MnO4- and Mn2+ in effluent streams and foods with a relative standard deviation better than 1.85%. A sampling frequency of up to 24 h(-1) can be achieved. Interfering ions can be removed by an ion-exchange column built into the flow injection system.