The effect of different ruthenium precursors on the structure and catalytic properties of the Ru/MgF2 system was studied with such methods as IR, XPS, EPR and catalytic test reactions. The adsorption of probe molecules (CO and O-2) revealed a greater ability to transfer an electron from ruthenium in the case of samples obtained from Ru-3(CO)(12) than in the case of samples obtained from RuCl3. Besides, metallic crystallites of different size were obtained depending on the precursor used. Namely, the average cluster size was 1.5 times smaller for carbonyl samples in comparison with chloride ones. Both series of preparations were active in redox or acid-base reactions. The activities of the carbonyl samples were higher than those of the chloride catalysts, particularly in reactions that require the presence of acid centers.