SUMMARYThree materials were tested in small-scale baskets of cubic dimensions and analyses were performed based upon the results according to the Frank-Kamenetskii (FK) method and the crossing point (CP) method.Comparison of the FK method and the CP method results was performed additionally. The activation energy E and the QA value were found. The relationship between critical ambient temperature and the storage size was determined as well as the relationship between CAT and time to maximum thermal runaway for the materials. Frank-Kamenetskii; crossing point method; spontaneous ignition, self-heating; wood pellets, protein powders SCOPEThe purpose of the investigation was to find the behaviour of different materials with regard to igniting spontaneously and to investigate the usefulness of two general known methods i.e. the Frank-Kamenetskii (FK) method [1-3] and the crossing point (CP) method [4][5][6]. The underlying results are described in six reports issued by the Danish Institute of Fire and Security Technology (DBI) [7][8][9][10][11][12]. In three reports the results of the small-scale tests were compared to observations Hamlet Protein A/S, a producer of protein powders for the animal food industry, did during an incident in their drying process filter. In three reports the results of small-scale test were carried out for wood pellets.