The dissertation investigates the physical and mechanical properties of the cellulose-based composite boards impregnated with hemp seed, linseed, or tung tree oil and the composition of the microorganism community affecting such materials. The investigations described in the dissertation aim to create the ecological protective coating from natural oils on the composite boards of lignocellulosic origin so that these would be resistant to mechanical, water effects, and the destructive impact of microorganisms and to elucidate the composition of microorganism community that degrades the lignocellulose.