A detailed investigation concerning the surface atomic structure of Au/Cr2O3 model catalyst deposited on a Pd(111) single crystal surface is presented. The system was prepared by MBE (Molecular beam epitaxy) and characterized in situ by LEED (Low Energy Electron Diffraction), XPS (X-ray Photoelectron Spectroscopy) and XPD (X-ray Photoelectron Diffraction). The element specific short-range order information was extracted from the XPD experiments supported by a comprehensive multiple scattering calculation diffraction approach. From the experiments we have strong evidences of Au islands formation on Cr2O3 surface. The experiments indicated that the islands are formed by two Au monolayers, as well as important structural relaxations in the three outermost atomic layers of the Au/Cr2O3 surface. Such a surface structure could explain the particular catalytic reactivity displayed by catalysts based on Au nanoparticles dispersed on several oxide matrices.