In this study, numerical simulation using Computational Fluid Dynamics (CFD) was conducted to predict the effect of various parameters on freezing time of slab shaped food by a slot air impingement. Continuity, momentum and energy equations were solved using Fluent 6.0 a commercial Computational Fluid Dynamics (CFD) solver. In order to model the turbulent air flow, the standard Reynolds Stress Model (RSM) was applied. The results of this study show that the freezing air temperature and velocity, nozzle to food spacing are important factors affecting freezing time of slab shaped foods. This study provides useful information for optimum design and operation of food freezers.