This work elucidates the exact chemical nature of the interfaces in (111) Au-Ni multilayers grown by molecular beam epitaxy. We performed an X-ray investigation combining fitting of symmetric X-ray diffraction (XRD) spectra, and anomalous X-ray scattering analysis. We unambiguously show that the interfaces Au/Ni are abrupt. whereas the Ni/Au ones extend on five planes. (C) 2002 Published by Elsevier Science B.V.