Abstract: Adsorption of carbon monoxide and the co-adsorption of hydrogen and carbon monoxide on alumina supported 4% ruthenium have been studied by the differential infrared spectroscopy. The bands of COadsorbed on ruthenium have been assigned. The band of medium frequency at 2070-2060cm^-1 is assigned to the overlap bands of symmetric stretching vibration of twin COand stretching vibration of linearly adsorbed CO. The influences of surface C (C_s), surface H (H_s) and surface O (O_s) on adsorption states of carbon monoxide are discussed. It is shown that the surface carbon formed by the disproportionation of CO enhances strengthening of Ru-CO bonding, however, the co-adsorption of hydrogen weakens strengthening of Ru-CO bonding. Surface oxygen impels to form the site deficient electron. Twin CO could be formed in the sites. Adsorption of twin CO is active adsorption.