The diploma thesis deals with evaluation of the determined results of sieve analysis, volumetric mass density and lower explosive limit of selected combustible dusts. These cumbustible dusts are dusts of european spruce and fibreboard. Samples of wooden dusts were made by belt sander with corundum sandpaper. Separation of rough sample from non-dusts particles and dusts particles were made by sieve analysation. That dust samples were further separate by size of particles according to the sieves which were used. On a sieve analysis was used gadget Retsch AS 200 according to TUZVO methodology. Volumetric mass density is its mass per unit volume. That volumetric mass density were made according to STN EN ISO 23145 – 1: 2016. The smallest amount of combustible dust which is still able to explode is called lower esplosive limit. These experiments were made in the blast chamber VK 100. By evaluation of results was found out that the lower explosive limit is influenced by different particles of dust, differences in sampling methodology and the batch enering the experiment. To design of effective explosion protection in plants, where these dusts is occured, is our findings important.