We report on ultra-high-vacuum depositions of thermally evaporated silver at different temperatures and coverages on a well-characterized thin magnesium oxide film, which is supported on a molybdenum single crystal. From electron energy loss (EELS, HREELS) and photoemission spectra (UPS, XPS), we propose a three-dimensional growth mode at room temperature. From temperature-dependent measurements between T=100 and 500 K, we deduce the sticking probability, S, for this system. (C) 1998 Elsevier Science B.V. All rights reserved.