A supercritical fluid is one that exhibits unique properties different from typical liquids or gases. Technologies utilizing supercritical fluids are termed supercritical technologies.

These fluids possess properties midway between those of gases and liquids, allowing them to rapidly alter their properties with slight changes in pressure and temperature without undergoing phase changes.
Due to the absence of surface tension, they can easily penetrate porous structures, exhibit excellent diffusion, and facilitate fast mass transfer. They are characterized by low viscosity, high diffusion rate, and strong solvency.