As part of EPA's continuing research on methods to control volatile organic compound emissions, a vapor-phase activated carbon pilot plant has been constructed. The automated, computer-controlled pilot plant has been designed to provide data not easily obtained from full-scale adsorption systems. As part of an overall testing program, the pilot plant was operated on an actual solvent-laden air stream at a manufacturing site. The purpose of the testing was to evaluate parameters affecting vapor-phase carbon adsorption and to determine if modifications to the existing adsorption system at the site would improve performance. The parameters investigated include relative humidity and temperature of the solvent-laden air stream, carbon type, the amount of steam used to regenerate the carbon, and the effect of cooling and drying the carbon bed after regeneration. The experimental conditions and the loading, expressed in pounds of volatile organic compound adsorbed per pound of activated carbon, are reported.