This paper focuses on the assessment of the inclination to self-ignition of various types of wood chips according to the methodology of European standard EN 15188. The study also assesses the effect of heating temperatures on the composition and quantity of gaseous products of heating. Gases were analysed using an infrared spectrometer with Fourier transformation. From the measured results it was found that the inclination to self-ignition differs for various samples of wood chips. The paper discusses certain parameters assumed to affect the inclination of biomass to self-ignite. When assessing the effect of temperature on the composition of gaseous products, a sample of forest wood chips heated at temperatures from 50 to 150 °C resulted in the following gaseous products: carbon dioxide, carbon monoxide, water and aliphatic hydrocarbons; their concentrations increase with the increasing temperature. Carbon oxides have been proposed as indicators of the state of stored materials self-heating. Observations presented in this paper can be used as data for elaborating safety instructions for storage of fuels based on solid biomass.