Polycrystalline pyrite films have been prepared by evaporation of Fe and S from separate molecular beam sources. It is shown by X-ray diffraction and by X-ray and ultraviolet photoelectron spectroscopy that at S pressures of 6-8.10(-5), Pa pyrite is formed at a substrate temperature of 390 K. At higher temperatures, pyrrhotite (Fe7S8) is present in the films.