Through an interplay between atomistic thermodynamics, isotherm models, and kinetics, all based on density functional theory calculations, we propose a mechanism for the removal of the (1x2) missing-row reconstruction on Au(110) under high CO pressure. Elevating the pressure from ultrahigh vacuum to one atmosphere causes the emergence of adsorption structures containing Au-CO entities. It is argued that the formation and the diffusion of these species may be the general phenomena which may control the morphology of metal surfaces under elevated CO pressure.