A CH3CN-modified triruthenium carbonyl cluster, Ru-3(CO)(9)(CH3CN)(3) (I), has been adsorbed on platinum and platinum oxide surfaces from dichloromethane solutions. The modified surface has been characterized by X-ray photoelectron spectroscopy (XPS) and polarized grazing angle Fourier transform-infrared (FT-LR) microscopy. The proposed mechanism for the adsorption of I involves the chemisorption of the metal cluster at the platinum surface by losing the acetonitrile ligand. The original cluster, Ru-3(CO)(12), could not be adsorbed under the same experimental conditions used for cluster I. The cluster modified surface was treated with hydrogen for the reduction of the cluster to its metallic state on the Pt surface. This was done at different temperatures. The XPS results show the formation of a complex Ru-RuO2-RuO3/Pt surface.