A two dimension mathematical model has been developed to simulate the coupled heat and mass transfer in a porous medium undergoing a strong endothermic chemical reaction. Differing from the traditional two phase equation model, just the temperature field of bulk flow is known from the solution of energy equation. The temperature distribution of the solid matrix is solved according to the reaction kinetics of the decomposition of calcium carbonate. The coupling of these two equations is given by the item of chemical reaction. The fluid flow is modeled by the Ergun-Forchheimer-Brinkman equation. This model is solved numerically by the alternate dimension implicit method, and the numerical results are validated by comparing with the experimental data in literature. The influence of the strongly endothermic chemical reaction on the heat and mass transfers in the porous medium is discussed. The reaction features of the packed bed of pellets are analyzed under different conditions by varying the key parameters. (C) 2007 Elsevier Ltd. All rights reserved.