Thin gold films are grown on Si and Ge substrates by galvanic displacement from fluoride-containing solutions. The physical and chemical properties of the metal-semiconductor interface are characterized by a variety of techniques, including photoelectron spectroscopy, atomic force microscopy, and electron microscopy. Displaced gold films exhibit strong adhesion to germanium substrates but not to silicon. This behavior is explained by the presence of a chemical bond at the Au-Ge interface, which is not observed in the Au-Si system. The implications of these findings for semiconductor metallization by galvanic displacement methods are discussed.