The adsorption of sulfur compounds from high-sulfur fuels onto metal surfaces and their propensity for subsequent desorption when the metal then contacts a low-sulfur fuel were measured for carbon and stainless steels, copper, and a copper-nickel alloy. Treatments were carried out in a variety of liquid fuels with a large range of sulfur concentrations. Of the common metals that come in contact with fuels, copper alloys had the greatest potential for contributing to sulfur contamination because of the high sulfur adsorption/desorption activity of copper. Carbon steel, which is the primary material for pipelines transporting finished fuels, shows virtually no potential for causing contamination of low-sulfur fuels, while stainless steel is only slightly more active. Polymeric materials, such as fiberglass-reinforced plastic, which is a common material used for manufacturing fuel storage tanks, have a greater potential for sulfur contamination of fuels than most metals, because fuel can be adsorbed and released from the polymeric framework of the material as it swells and shrinks.