The most common definition of supercritical fluid would be "non-condensable fluid compressed to high density above the critical temperature." Supercritical fluid has the large thermal motion of the molecule because it exceeds the critical temperature. It could be controlled the density corresponding to the liquid from a dilute state close to the ideal gas density, as a factor of operating temperature and pressure. The equilibrium and transport properties of supercritical fluids can be controlled as a function of density. Therefore, supercritical fluid could be considered a new innovative solvent.

Studies on the supercritical fluid of Japan have begun in the supercritical gas extraction and many research reports have been made around the Society of Chemical Engineers, Japan. In 1987, the Study Group of Advanced Use of Supercritical Fluids was inaugurated. In 1990, it has been approved by the Committee on Special Studies. A lot of seminars and symposium has been held as a core of research and information exchange in the field. While the practical examples of the process can be seen, the unique physical properties of supercritical fluid is now being actively studied from the viewpoint academic in basic research. The technology research for supercritical fluid of our country is a high reputation worldwide.

The Division of Supercritical Fluids was established on March 1, 2001, as a group specializing in research on supercritical fluid for domestic and international Society of Chemical Engineers, aimed at cooperation with other societies .