The effect of the kind of ruthenium precursor {Ru-3(CO)(12) or RuCl3.nH(2)O} and the activation conditions on the performance of Ru/MgF2 preparations in thiophene hydrodesulfurization has been studied. The highest activity, higher than that of the commercially available system CoMo/Al2O3, was revealed by the Ru/MgF2 catalyst sulfided in the 50% H2S/He atmosphere. According to the results of TPR study, this preparation was characterized by exceptionally high content of RuS2, which seems to be responsible for its high activity. As follows from the product distribution of thiophene HDS, the activation in the H2S/He atmosphere mainly leads to the formation of saturated products (butane), while the activation in the atmosphere of H2S/H-2, to the formation of unsaturated products (butene-1, cis- and trans-butene-2).