The aim of this work was to obtain eco-friendly constituents for making wood-polymer composites (WPCs) by rational utilisation of hardwood residue with its mechanical processing and purposeful chemical modification. To reduce the energy input for residue milling for obtaining a lignocellulosic filler as well as to activate its surface for the further modification, the optimal parameters of low temperature acid hydrolysis of the hardwood residue under mild conditions were found. To enhance the wetting of the lignocellulosic filler with respect to recycled polypropylene, the milled hydrolysed wood particles were modified by ammoxidation. For obtaining a lignincontaining surface tension regulator (compatibiliser) that is able to reinforce the interaction between the constituents at the interface, soda lignin was obtained via delignification of the hydrolysed hardwood residue under laboratory conditions. The developed compatibiliser represented nanoparticles of a non-stoichiometric polyelectrolyte complex, incorporating soda lignin and synthetic polyamine-polyethylenimine. By using appropriate laboratory equipment and the determined technological regime, aspen wood-recycled polypropylene composites were made and tested.