A supercritical fluid is the phase of material at critical temperature and critical pressure of the material. Supercritical fluids combine useful properties of gas and liquid phases, as it can behave like both a gas and a liquid in terms of different aspects. Carbon dioxide and water are the most commonly used supercritical fluids, as they are used for decaffeination and power generation, respectively. In general terms, supercritical fluids have properties between those of a gas and a liquid.