The temperature-programmed reaction (TPR) technique coupled with infrared (IR) spectroscopy has been employed to study the reactivity of adsorbed CO towards hydrogen. The combination of the two techniques provides information on the structure and reactivity of adsorbates, activation energy and kinetic data for the CO hydrogenation reaction. CO adsorption on Rh/SiO2 at 298 K produced mainly linear and bridged CO on the surface. Linear CO appears to be more reactive than bridged CO in the formation of methane during TPR over Rh/SiO2. The addition of silver to Rh/SiO2 promotes the formation of gem-dicarbonyl CO and suppresses the formation of bridged CO during CO adsorption at 298 K. The disproportionation of gem-dicarbonyl CO and the reduction of Rh+ by oxidation of the CO ligand of Rh+(CO)(2) produce CO, CO2, and surface carbon on the Ag-Rh/SiO2 catalyst at temperatures above 310 K. Hydrogenation of surface carbon begins at 390 K leading to methane formation. The methane peak temperature was observed at 442 K on the Ag-Rh/SiO2 and at 420 K on Rh/SiO2. The higher hydrogenation temperature of adsorbed CO and surface carbon over Ag-Rh/SiO, as compared to Rh/SiO, is attributed to the suppression of hydrogenation by Ag.