Abstract: The highly and less extractable species.of RuNO nitro complexes in nitric acid can be isolated by TBP extraction chromatography and cation exchange. RuNO(NO2)2(NO3)2(H2O) and RuNO (NO2)3(NO2) (H2O)-which exist in fresh stock solution, are not stable in the solution. The species which have been aged for 24 hours are converted into RuNO(NO2)2(NO3)(H2O)2 and RuNO (NO2)(NO3)2(H2O)2 at normal temperature (20℃). These four complexes are highly extractable species.