During the last 25 years there is an increasing interest in the research of the use of compressed gases as solvents in extraction processes. The main advantage of a gas in relation to a liquid is the ease of separating the solvent from the product. The volatility of a gas is higher which means that less solvent will remain in the product. In food-industries this can be very important since many solvents are toxic and are not allowed in products to be sold. The use of compressed gases at near critical conditions will be discussed in chapter 2. Triglycerides, the basic product of food-industries, form an important group· of natural products since they provide energy sources in many of our foodstuffs. The very wide range of triglycerides found in nature arises from the combination of a relatively small number of fatty acids with glycerol, the positional isomerism of fatty acids· being responsible for the multiplicity. In this work research was done on the phase behaviour of propane and the mono-acid triglyceride tripalmitoylglycerol, in short tripalmitin. In the near future research will also be carried out on the systems propane- tristearin and propane-triolein. By possessing reliable basic data of these key-component systems we will try to predict the phase behaviour of other analogous propane-triglyceride systems. This will probably allow us to make predictions of selectivity and solvent-capacity in extraction processes with these components. In the discipline of applied thermodynamics there is an increasing interest in the phase behaviour of systems containing small and large molecules. Particularly in extraction processes this is important, since many hydrocarbon solutes are much larger than the solvents used for their extraction. In the early sixties Rowlinson and Davenport investigated the phase behaviour of methane and larger hydrocarbons as a function of the carbon number, the number of side-branches, and the degree of saturation. They ·were the first to give such a quantitative overview with that specific background. Later similar types of phase behaviour for other binary systems containing small and large molecules were found ( Paas et al. 1979 , van der Kooi 1981, De Loos 1984 and Peters 1986 ).