The reaction of several clusters containing nitric oxide ligands with molecular hydrogen has been studied. For HRu3(CO)10(NO) the products are H2Ru3(NH)(CO)9, HRu3(NH2)(CO)10, H4Ru4(CO)12, trace amounts of H3Ru4(NH2)(CO)12, and a hexane-insoluble, THF-soluble precipitate. The compounds have been characterized by spectroscopy (including 15N NMR) and for HRu3(NH2)(CO)10 by a singlercrystal X-ray crystallographic analysis (monoclinic crystal system, P21/a space group, a = 11.778 (3) Å, b = 11.928 (3) Å, c = 12.010 (4) Å, β = 98.54 (2)°, Z = 4). A system was built that allowed the reactions to be followed directly by high-pressure liquid chromatography. A kinetic analysis of the disappearance of HRu3(CO)10(NO) revealed that the reaction is first order in cluster concentration and is inhibited by CO. The rate also depends on the pressure of H2, exhibiting a saturation effect above 1400 psig. The reduction of Ru3(NOCH3)(CO)10 yields a product distribution similar to that found for HRu3(CO)10(NO) with the important exception that no hexane-insoluble species is formed. Methanol is isolated from this reaction. The major product resulting from the reduction of Ru3(NOH)(CO)10 is the same hexane-insoluble product as found for HRu3(CO)10(NO). A discussion of the mechanism of these reactions based upon the observations is presented.