A steady-state mathematical model to calculate heat and mass transfers during the baking of thin cereal products (biscuit type) in a continuous, indirect, gas-fired oven, is presented. The basic principles and equations of the model are discussed. The temperature and composition of the baking atmosphere and biscuit on a transversal oven section are assumed to be uniform. The model takes account of heat transfer by radiation, convection and conduction as well as product-water phase change. For mass balances, the model takes account of the possible condensation of steam from baking atmosphere to product surface and product drying. An experimental study performed on a continuous, indirect, gas-fired, pilot plant oven for biscuit baking was used to validate the model, and good agreement was obtained between predicted and measured values.