In an effort to demonstrate that Ru(NH3)(5)(H2O)(2+) can be used to remove dibenzothiophene from hydrotreated petroleum feedstocks, this metal complex was reacted with a variety of thiophenes (Th*), including dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-Me-2-DBT) to give complexes of the type Ru(NH3)(5)(Th*)(2+). This ability of Ru(NH3)(5)(H2O)(2+) to bind to thiophenes has been used in an extraction process in which a solution of Ru(NH3)(5)(H2O)(2+) in 70% DMF and 30% H2O is contacted with a simulated petroleum feedstock (45% toluene/55% hexanes) containing 400 ppm of DBT. One extraction removes 50% of the DBT from the feedstock phase as Ru(NH3)(5)(DBT)(2+), which is present in the DMF/H2O phase. Five successive extractions reduce the amount of DBT in the simulated feedstock from 400 to 25 ppm. The Ru(NH3)(5)(H2O)(2+) extractant can be regenerated from the Ru(NH3)(5)(DBT)(2+) either by air-oxidation followed by H-2-reduction or by displacement of the DBT by adding H2O to the DMF/H2O phase. Extraction of 4,6-Me2DBT from the simulated feedstock using Ru(NH3)(5)(H2O)(2+) in 70% NN-dimethylacetamide and 30% H2O was less successful as the 4,6-Me2DBT concentration was only reduced from 400 to 340 ppm.