A numerical model for predicting temperature and velocity fields during conjugate heat transfer in a high pressure (HP) (similar to 200 MPa) thawing process presented. This model considers the apparent specific heat formulation to solve the energy equation with phase change and the shift approach to extrapolate thermophysical properties at HP. It does not require the adjustement of the convective heat transfer coefficient. The compressible flow of water in the HP vessel is calculated. It is shown that the fluid motion is dominated by forced convection in the compression phase and by natural convection during the holding phase. A very good agreement between numerical and experimental results is obtained. Additional simulations carried out at various pressures permit to assess the influence of the pressure level on the thawing time. The analysis of the phase change inside the food and of the velocity field inside the vessel clearly demonstrates the great potential of this model to optimize this HP process at an industrial scale. (c) 2007 American Institute of Chemical Engineers.