The safe storage, processing and handling of coals and biomass resources requires their tendency to self-ignite be understood; fires caused by self-ignition have occurred on many occasions in ports and at industrial plants. This work provides information on the tendency of several types of coal and four types of biomass to self-ignite. Data were obtained using the isothermal oven procedure and analyzed using the Frank-Kamenetskii method and a scaling procedure, both contemplated in standard EN15188. The results obtained throw light on the optimum volumes and storage times of the studied materials. The results also validate the methodology followed for determining the risk of self-ignition. (C) 2012 Elsevier B.V. All rights reserved.