The adsorption and reaction of CO2 were examined on Ag(110) precovered with submonolayer amounts of cesium and precovered with cesium and oxygen. Cesium promotes the adsorption of CO2 at 325 K but not to the extent found in earlier studies for oxygen-precovered Ag(110). The adsorbed species is most likely a surface cesium carbonate, which decomposes at higher temperatures than the surface carbonate formed on oxygen-precovered Ag(110). When both cesium and oxygen are preadsorbed, CO2 adsorption increases dramatically, where again the adsorbed species is a carbonate. An increase in the corrugation of the electrical field near the surface is proposed as a reason behind the synergetic CO2 adsorption on the cesium- and oxygen-precovered Ag(110) surface.