Wood may contain several harmful chemicals which can be removed by high-temperature treatment. This is essentially a drying process under linearly increased gas temperature up to final gas temperature of 220-230 degrees C which is a challenging process to model. The effective model is useful in process design, evaluation of equipment performance, and troubleshooting. In this study, the REA (reaction engineering approach) is implemented to describe the local evaporation/condensation rate and combined with a system of equations of conservation to yield a spatial model, called the spatial reaction engineering approach (S-REA), in order to model the heat treatment of wood under constant heating rate. A good agreement between the predicted and experimental data is observed. The REA is accurate to model the local evaporation rate of the heat treatment of wood. The S-REA is an effective nonequilibrium multiphase approach to model the heat treatment of wood, a simultaneous heat and mass transfer process involving water transformation under linearly increased gas temperature.