ABSTRACT
When I received the letter from Professor Jo´zsef To´th inviting me to prepare a chapter of the
book in the area of ‘‘adsorption isotherms for the supercritical region,’’ I hesitated to accept. As
mentioned by several well-known researchers [1-4], there are not many articles that present
original experimental data or discussions relating to the mechanism of the physical adsorption of
fluids at above-critical temperatures. As consequence, there may be as many points of view
regarding the nature and theory of supercritical adsorption as there are researchers. To construct
the text of the chapter was indeed a difficult job because several serious questions have to be
answered without a sophisticated textbook on which to rely. The context will inevitably reflect
mainly the opinions and biases of the author. Nevertheless, the invitation was attractive and
despite initial reservations, I concluded that such an exercise was indeed useful, especially if it
prompts others to think about these issues and perhaps to challenge the opinions expressed here.
