There has been rising concern in recent years over supercritical fluids for organic waste treatment and other applications. The discovery of the presence of critical point dates back to 1822. The temperature and pressure beyond the critical point are in the supercritical state. Critical points are usually at high pressures. Therefore, a high-pressure test facility (high temperature and high pressure depending on the case) is required for a systematic study of fluids in the near- or supercritical state. This might have been the main reason why studies in this field were comparatively few until recently. Research on supercritical fluids and the applications development reached the initial peak during the period from the second half of the 1960s to the 1970s followed by the secondary peak about 15 years later. The initial peak was for the separation and extraction technique as represented by the extraction of caffeine from coffee beans. Since the practical application in Germany in 1978, a number of practical plants have been in operation. The secondary peak concerns decomposition of organic (waste) substances, which started when the U.S. Department of Defense began studies on using supercritical water as a means for completely decomposing chemical weapons. And the tertiary peak is about to come with mounting interest in the possible development of new material program.