Biodegradable composites were prepared from wood flour of sawmill residues and a thermoplastic starch (Mater-Bi TM and glycerol). For the preparation of the composites flour from sawmills of four wood species (spruce, pine, beech and poplar), three particle sizes (<150, 150-250, and 250-750 lm) and in six proportions (10,20,30, 40, 50, and 60% wt) was used. The composites were characterized by means of mechanical property measurements, scanning electron microscopy, water absorption, thermal stability and biodegradation studies. Addition of wood flour to thermoplastic starch increased significantly tensile strength, modulus of elasticity, elongation and thermal stability and decreased water absorption and biodegradation rate of the composites. Almost all the properties of the composites increased with increasing wood flour content and decreasing particle size of the flour. Tensile strength increased up to 50% wt but decreased at 60% wt content of wood flour. The softwood species (spruce, pine) gave better mechanical, thermal and water absorption properties, but lower biodegradation rate than the hardwood species (beech, poplar).