Hydrocarbon fuels containing elemental sulfur can cause copper and copper alloy components of a fuel delivery system to severely corrode. Experiments were undertaken to study the composition, thickness and rate of growth of films formed in sulfur containing fuels. The time dependent growth of these films was studied using Auger electron spectroscopy in combination with standard ion sputtering techniques. Initially, the thickness of the films increased rapidly, but slowed after longer exposures. This behavior was shown to obey the parabolic law that is used to describe oxide film growth in air. The relative amount of sulfur in a layer directly beneath a thin hydrocarbon overlayer was found to increase with exposure of copper to the fuel. For long exposures this layer appeared to be predominantly CuS with Cu2-xS and then Cu2S below it, while the film was composed of predominantly Cu2S after short exposures to the hydrocarbon. X-ray photoelectron spectroscopy supported this conclusion.