This article deals with study of minimum ignition temperature (MIT) of thermally modified spruce dust. Dust of several species of spruce was mixed, sieved, dried and subjected to Thermo-S temperature programme. Samples of dust (200 250 μm) were tested in Goldbert-Greenwald furnace apparatus for determination of the MIT of dust clouds. The influence of air pressure and sample weight to the MIT was studied. The results show that the MIT of thermally modified spruce dust gradually decreases as the sample weight and air pressure rise. The lowest value of MIT (470 °C) was measured, when the air pressure was 50 kPa and the sample weight 0,5 g. To reach even lower values of MIT (˂468 °C), the air pressure should gradually rise to approx. 42 46 kPa and the weight of dust sample should be approx. 0,46 0,53 g.