One major concern when it comes to storage of wood pellets is the risk for self-heating. The propensity for self-heating varies between different types of pellets. It also depends on how the pellets have been handled and on the storage conditions, e.g. the temperature and humidity. Within the framework of the research project “Large scale Utilization of Biopellets for Energy Applications –LUBA” different laboratory-scale methods have been used to study different thermal properties and the propensity for self-heating for different types of pellets. The different methods used include micro calorimetry also called isothermal calorimetry, basket-heating tests and transient plane source (TPS). In total 21 different pellets samples were tested in the micro calorimeter, three in the basket-heating test and three in the TPS. The samples showed significant differences in propensity for self-heating. Differences could be seen both between different types of pellets and depending on the age of the pellets. Comparing the reactivity rates from the basket-heating tests and those from the isothermal calorimetry tests with the same type of pellets, both methods gave the same ranking of reactivity. It was shown that the TPS-method is applicable for the determination of thermal properties both for measurements on single pellets and for measurement on bulk pellet material.