<b>Abstract</b>— <p>The article presents research on the development of a composite material with improved performance. The growing industrial and academic interest in the selection of wood flour as a reinforcing filler in polymer composites and its preference over synthetic fibers is based on their superior mechanical properties, low density, abundance, and recyclability. With the aim of improving interfacial adhesion between the matrix and filler, various processing aids have been used to improve compatibility. Wood polymer composites (WPC) have been made from wood flour and four types of plastics, such as polyethylene, polystyrene, ABS (acrylonitrile butadiene styrene), and SAN (acrylonitrile-styrene copolymer). Experimental studies have been carried out using impact strength and tensile and compressive strength tests, as well as measurements of the expansion coefficient over the water absorption thickness. The effect of various technological additives on the mechanical properties of composites has been studied. The results show that processing aids can increase the bond strength of wood flour to the polymer and improve the mechanical properties of the composites. Comparatively better results are obtained using a processing aid in the form of an isocyanate resin. The wood–polymer composite combines the properties of wood flour and polymer, with water resistance, dimensional stability, and dynamic strength.</p>