Observations of supercritical adsorption reported before 1930 was covered in studies by McBain and Britton. All of the important articles on this subject published between 1930 and 1966 have been reviewed by Menon. During the last 20 years, a growing interest in supercritical adsorption research under the impetus of the quest for clean alternative fuels has been observed. Considerable progress has been made in both adsorption measurement techniques and molecular simulation of adsorption on computers, rendering new insights into the nature of supercritical adsorption.