The surface-mediated reductive carbonylation Of SiO2-supported RuCl3 and Ru(NO)(NO3)(3) has been studied by IR spectroscopy. Hydrated RuCl3/SiO2 reacts readily with CO (100-700 Torr) to form a mixture of Ru(CO)Cl-2(HOSi)(3) and Ru(CO)(2)Cl-2(HOSi)(2) at 25 degreesC, and a mixture of Ru(CO)Cl-2(HOSi)(3), Ru(CO)(2)Cl-2(HOSi)(2), Ru(CO)(3)Cl-2(HOSi) (major product) and [Ru(CO)(3)Cl-2](2) at 100 degreesC. Hydrated Ru(NO)(NO3)(3)/SiO2 reacts readily with CO to give a mixture of Ru(CO)(2)(OSi)(2) and Ru(CO)(3)(OSi)(2) at 25 degreesC. At 100 degreesC, hydrated Ru(NO)(NO3)(3)/SiO2 is converted to a mixture of Ru(CO)(2)(OSi)(2) and Ru(CO)(3)(OSi)(2) under 100 Torr of CO, and a mixture of Ru-3(CO)(12) (good yield) and RU(CO)(3)(OSi)(2) under 700 Torr of CO. All these results are demonstrated by surface IR spectra and extraction experiments with organic solvents. While the carbonylation of hydrated RU(NO)(NO3)(3)/SiO2 proceeds, the stoichiometric reductions of NO3- and NO: 2NO(3)(-) + 3CO + 2HOSi --> 2NO + 3CO(2) + H2O + 2OSi(-) and 2NO + CO --> N2O + CO2 are suggested to occur on the surface, according to gaseous IR observation. The proportion of ruthenium(II) tricarbonyl species is found to increase with the increases of carbonylation temperature and CO pressure. In addition, the detrimental effect of calcination of RuCl3/SiO2 and Ru(NO)(NO3)(3)/SiO2 at 400 degreesC on the reductive carbonylation is discussed.