A new mathematical model for numerical simulation of two dimensional food freezing due to natural convection is presented. Fluid mechanics and heat transfer by natural convection between air and a solid food in a freezer are predicted along with the heat conduction inside a plate shaped Food. The mathematical model used includes continuity, linear momentum and energy partial differential equations for air and the non-linear heat diffusion equation for the solidification of the x ater content in the food. Unsteady two dimensional results of the velocity and temperatures distributions in the air around the food obtained by using the finite volume method are presented. Experimental data of temperature variation in time for a slab shaped food inside a freezer are used to assess the accuracy of the mathematical model and the solution procedure. It is found that the use of this model, that does not require heat transfer coefficients. allo vs to simulate two dimensional freezing experiments in a slab shaped food by natural convection with maximum and mean deviations of 5.2% and 1.2%, respectively. (C) 2002 Elsevier Science Ltd. All rights reserved.