The reaction routes between co-adsorbed CO and O on kinked Au(321) slabs were analyzed theor. Complexes of vicinal type react most easily with calcd. barriers from 0.05 to 0.3 eV, whereas the more strongly coadsorbed geminal structures do not react directly unless surface oxygen is present in excess. Generally, the activation energy of CO2 formation from vicinal complexes remains low and that from geminal complexes increases, when Ag impurities are introduced. The results can be generalized to other rough gold surfaces, particularly, helping to understand the formation of CO2 above 200 K, as obsd. in the temp. programmed desorption studies of nanoporous gold, a monolithic nanostructured gold catalyst.