The influence of a Co seed layer on the structure of Au films grown onto alpha-Al2O3(0 0 0 1) single crystal substrates by molecular beam epitaxy has been studied by reflection high energy electron diffraction (RHEED). The RHEED results proved that the initial deposition of a few monolayers of Co onto Al2O3(0 0 0 1) prior to the Au deposition yielded high-quality fcc Au(I I I)-oriented epitaxial films and a well-known (23 x 1) surface reconstruction structure. Based on the RHEED results, it was concluded that the adhesion energy between the Co seed layer and Al2O3 substrate was rather important than the lattice mismatch between them. (c) 2006 Elsevier B.V. All rights reserved.