The consumption of plastic materials has increased enormously due to their various advantages. Recycling and reusing plastics, as well as wood waste, are the processes to reduce the environmental pollution. Utilization of secondary plastics for manufacturing wood–plastic composites (WPCs) has gained considerable attention and it is now a constant concern for researchers. In the case of clay reinforced WPCs (having polymers of low polarity, such as polypropylene (PP), as matrix), the low compatibility between the polymer and clay was observed, this leading to poor dispersion. The use of maleated polypropylene (MAPP) as compatibilizer enhances the dimensional stability and mechanical properties of these nanocomposites by improving adhesion between PP and wood particles, as well as interactions between PP and clay. This paper aims to evaluate the effect of organically modified montmorillonite (Cloisite 15A) as reinforcement for secondary polypropylene-wood flour composites obtained by melt-blending method. Pure PP was used as reference. Nanocomposites morphology was analyzed by scanning electron microscopy and results showed increased d-spacing of clay layers, which is an indication of enhanced compatibility between PP, clay and wood flour. It was also found that nanocomposites properties vary slightly in the series, while the impact and flexural strength of the pure and secondary PP differ significantly.