The dissertation work The influence of the characteristics of wood dust on the spread of fire in woodprocessing industry characterizes qualities and chemical composition of wooden dust and fire risk in settled or swirling form. The aim of the work is setting the lower explosive limit, the speed of fire spread across settled wood dust surface, determination of combustion heat, calorific value of chosen wood species and determination of the thermal decomposition products. To achieve the goals of the work scots pine, white fir, norway spruce, common beach, sessile oak and mixtures of them were chosen. Setting the lower explosive limit of these types of wood dust was conducted on two fractions: f < 0,355 mm and 0,355 – 0,5 mm in an explosion chamber VK 100. The tests were performed on samples of wood parts and mixtures of wood and bark. It was proved that higher values of lower limit of explosiveness were shown by samples of types of coniferous wooden dust. Combustion heat and calorific value of chosen wooden types were set as well. The resulting values clearly prove the impact of humidity and bark content on combustion heat and calorific value. With increasing humidity the measured values lowered. The results were supplemented with an analysis of volatile products arising from thermal decomposition in the temperature range from 150 °C to 300 °C by the method of gas chromatography-mass spectrometry. The compounds such as α-pinene, limonene, levoglucosane, furfural and others were identified.