Optimum growth conditions of epitaxial Au/Co/Au sandwiches with a strong perpendicular magnetic anisotropy have been investigated. The thermally induced evolution of the sandwich morphology, which determines its magnetic properties, was studied by means of reflection high-energy electron diffraction and Auger electron spectroscopy. The roughness of Au and CO surfaces, affected by the sample annealing, was evaluated from the length-dependent variance of topography acquired by atomic force microscopy.