Adsorption and reaction of CO and CO_2 were studied on oxygen-covered Au(997) surfaces by means of temperature- programmed desorption/reaction spectroscopy. Oxygen atoms(O(a)) on Au(997) enhances the CO_2 adsorption and stabilizes the adsorbed CO_2(a), and the stabilization effect also depends on the CO_2(a) coverage and involved Au sites. CO_2(a) desorption is the rate-limiting step for the CO+O(a) reaction to produce CO_2 on Au(997) at 105 K and exhibits complex behaviors, including the desorption of CO_2(a) upon CO exposures at 105 K and the desorption of O(a)-stabilized CO_2(a) at elevated temperatures. The desorption of CO_2(a) from the surface upon CO exposures at 105 K to produce gaseous CO_2 depends on the surface reaction extent and involves the reaction heat-driven CO_2(a) desorption channel. CO+O(a) reaction proceeds more easily with weakly-bound oxygen adatoms at the(111) terraces than strongly-bound oxygen adatoms at the(111) steps. These results reveal complex rate-limiting CO_2(a) desorption behaviors during CO+O(a) reaction on Au surfaces at low temperatures which provide novel information on the fundamental understanding of Au catalysis. Adsorption and reaction of CO and CO 2 were studied on oxygen-covered Au (997) surfaces by means of temperature- programmed desorption / reaction spectroscopy. Oxygen atoms (O (a)) on Au (997) enhances the CO 2 adsorption and stabilizes the adsorbed CO_2 (a), and the stabilization effect also depends on the CO_2 (a) coverage and involved Au sites. CO_2 (a) desorption is the rate-limiting step for the CO + O (a) reaction to produce CO_2 on Au ) at 105 K and exhibits complex behaviors, including the desorption of CO_2 (a) upon CO exposures at 105 K and the desorption of O (a) -stabilized CO_2 (a) at elevated temperatures. The desorption of CO_2 (a) from the surface upon CO exposures at 105 K to produce gaseous CO_2 depends on the surface reaction extent and involves the reaction heat-driven CO_2 (a) desorption channel. CO + O (a) reaction more easily with weakly bound oxygen adatoms at the ( 111) terraces than strongly-bound oxygen adatoms at the (111) steps. These results reveal complex rate-limiti ng CO_2 (a) desorption behaviors during CO + O (a) reaction on Au surfaces at low temperatures which provide novel information on the fundamental understanding of Au catalysis.