The thawing process is a unit operation that exposes the food to risk of microbial growth. To evaluate this risk, numerical modelling is very useful. The thawing process by means of a 3-D numerical model is investigated. Both heat diffusion with phase change inside the product and on the convection phenomenon in the heating medium is focused on. This coupled model does not require an a priori knowledge of the convective heat-transfer coefficient. The corresponding highly nonlinear equations were solved using a CFD software. Experimental investigations were carried out on a high-pressure vessel (temperature measurements), and on a specific device (velocity measurements). Comparisons between experimental and numerical results were very satisfactory, especially for transient temperature predictions. The model could then be exploited to assess process modification, and could be extended to investigate innovative processes at high-pressure. (c) 2006 American Institute of Chemical Engineers.