High hydrostatic pressure (HHP) has become in the last few years in a promising technology in food processing and preservation. HHP treatment of foods always results in a temperature increase due to the work of compression. Our main goal (project AGL2000-1440-C0201 involving specialists from Applied Mathematics of the Univ. Complutense de Madrid and the Instituto del Frio of the CSIC) is the modeling, mathematical analysis and numerical approximation of the process in devices with different dimensions, different pressurising fluids or different thermoregulating systems. The extent of it depends mainly on the composition of the food, its initial temperature, the pressurising fluid and the applied pressure and can be calculated improving the results by Otero et al. [2000] and other authors.