Wood pellets release heat and gases during storage. A TAM air isothermal calorimeter was used to measure the rate of heat release by bulk pellets at temperatures ranging from 30 to 50 degrees C. The results showed that self-heating rate at the tested temperature range strongly depended on the reaction temperature and the age of pellets. Heat release rate increased as the reaction temperature increased but the rate was not sensitive to pellets moisture content. The activation energy of the self-heating reaction increased with the age of pellets. A simple global kinetic model for self-heating was developed from the experimental data. The model can be applied to simulate the self-heating process in pellets storage containers at different storage temperatures and age of stored pellets. (C) 2014 Elsevier Ltd. All rights reserved.