The SFT Phase Monitor II is a powerful analytical tool for determining the solubility parameters of compounds and mixtures in subcritical and supercritical fluids. It provides direct, visual observation of materials under conditions precisely controlled by the user. Experiments can be performed in liquid or supercritical carbon dioxide and in other liquefied gases. Additionally, the effect of co-solvents on the solubility of compounds in supercritical carbon dioxide can be investigated with this instrument. It allows the end user to view dissolution, precipitation, and crystallisation of compounds over a wide range of pressures and temperatures.