By exploiting thermodynamic phenomena in systems with compressed gases, the properties of products such as their morphology and the size of particles and fibers can be tailored to industrial needs. Separation of complex mixtures can be accomplished. Processes that are conventionally operated in a number of costly steps can be reduced to a few operations. This article gives a phenomenological classification of such processes and explains the underlying principles. Operations developed on a laboratory scale as well as those already established in industry will be discussed.