The adsorption of sodium myristate from 0.1% aqueous solution by a series of carbon blacks and an activated charcoal has been measured at 70 °C. In every case a preferential adsorption of fatty acid was observed. The extent of adsorption of both the fatty acid and alkali components of the soap increased with decreasing particle size, i.e., with increasing surface area, of the carbons. The adsorption by activated charcoal was considerably higher than that obtained with even the finest of the carbon blacks.