This document specifies basket heating tests for the characterization of self-heating properties of solid biofuel pellets. This document includes: a) a compilation of basket heating test methods; b) guidance on the applicability and use of basket heating tests for solid biofuel pellets; c) information on the application of basket heating test data for calculations of critical conditions in storages. Data on spontaneous heat generation determined using this document is only associated with the specific quality and age of the sample material. The information derived using this document is for use in quality control and in hazard and risk assessments related to the procedures given in ISO 20024. The described methods can be used for other substances than solid biofuel pellets (e.g. wood chips).