The growth of ultrathin gold films on copper phthalocyanine film has been studied by means of photoemission spectroscopy. Different photon energies have been used in order to investigate the diffusion of Au atoms inside the organic film. The evolution of the Au4f peaks suggests the formation of small clusters. The valence-band spectra, acquired using different photon energies, indicate that these clusters diffuse inside the organic film. The growth of these clusters influences the electronic properties of the organic film. In fact, the core levels of the organic films show a charge transfer from the Au particles to the CuPc molecules, determining a shift of some components of the organic core levels. Spatially resolved photoemission spectra evidence the homogeneity of the gold film, which is not influenced by the CuPc surface defects. (C) 2004 American Vacuum Society.