A simple, sensitive and selective method has been proposed for spectrophotometric determination of ultra trace amounts of ruthenium based on its catalytic effect on the oxidation of pyronin B by periodate at ? max=555 nm. The described method is able to quantitize ruthenium in the range of 0.1-100 ng ml -1 (r=0.9973), with a detection limit 0.036 ng ml-1. Under optimum conditions, this procedure has been successfully applied to determine the trace levels of ruthenium in the environmental and biological samples. The precision, expressed as relative standard deviation of three measurements, is better than 2.24%. In part two a rapid and sensitive flow injection catalytic method was presented for determination of ruthenium based on its catalytic effect on the oxidation of pyronin B by periodate in pH =1.0. The reaction rate is controlled specrophotometricaly by monitoring the dye absorbance at 555 nm. The optimized conditions make it possible to determine ruthenium in the ranges of 0.1-10.0ng mL-1 (r2 =0.9982) and 10.0-50.0 ng mL-1 (r2 =0.9934) with a detection limit of 0.04 ng mL-1and a sample rate of 30 ± 5 samples/h. Relative standard deviation for the results of five replicate measurements does not exceed 1.44%.The proposed method has been successfully applied for quantitation of ultra trace amounts of ruthenium in some environmental and biological samples.