A sensitive catalytic spectrophotometric method for the determination of ruthenium (III) has been devel- oped, based on its catalytic effect on the oxidation reaction of methyl green with potassium bromate in acid solution medium at 100 ℃ . The above reaction is followed spectrophotometrically by measuring the decrease in the absorbance at 625 nm for the catalytic reaction of methyl green. The calibration curve for the recommended reaction-rate method was linear in the concentration range over 0.00–0.80 μg/L and the detection limit of the method for Ru (III) is 0.006 μg/L. Almost no foreign ions interfered in the determination at less than 25-fold concentration of Ru (III). The method is highly sensitive, more selective and very stable, and has been successfully applied for the determination of trace ru- thenium in some ores and metallurgy products. A sensitive catalytic spectrophotometric method for the determination of ruthenium (III) has been devel- oped, based on its catalytic effect on the oxidation reaction of methyl green with potassium bromate in acid solution medium at 100 ° C. The above reaction is followed spectrophotometrically by measuring the decrease in the absorbance at 625 nm for the catalytic reaction of methyl green. The calibration curve for the recommended reaction-rate method was linear in the concentration range over 0.00-0.80 μg / L and the detection limit of the method for Ru (III ) is 0.006 μg / L. Almost no foreign ions interfered in the determination at less than 25-fold concentration of Ru (III). The method is highly sensitive, more selective and very stable, and has been successfully applied for the determination of trace ru- thenium in some ores and metallurgy products.