Wood and wood dust pose a fire risk in wood processing industry, so it is important to investigate their burning mechanism. In the first part of the work, we determined the physico-chemical and anatomical properties of wood and wood dust and characterized the flame and the flame propagation. The main goal of this bachelor's thesis was to characterize the flame spread over compact wood and over a layer of settled wood dust, which we defined together with the partial goals in the second part. In the third and the fourth part, we processed knowledge about changes in the chemical and anatomical structure of wood by the effect of thermal energy. Based on the literature research, in the fifth and sixth part of the work we summarized the parameters that affect the flame spread and lastly evaluated the results.