The Wax appearance temperature as well as the amount and composition of wax precipitation were determined as a function of pressure in a synthetic complex system tetracosane + (multiparaffinic commercial wax). Measurements were performed by using two different experimental techniques: A high pressure microscopy apparatus for the solid-liquid phase boundary measurement. A filtration apparatus coupled to a chromatographic analysis of the partially frozen mixtures for the determination of the solid phase behaviour. Experimental results were compared with the values calculated by a predictive model. The influence of pressure on wax formation is shown to be as important as the influence of temperature and the model used can provide an excellent description of the melting behaviour over a wide pressure range. (C) 2004 Elsevier Ltd. All rights reserved.