Two industrial wastes fly ash and polypropylene was used to develop novel composite materials. The fly ash (FA) particles were coated with stearic acid (SA) and palmitic acid (PA) in 1 wt% concentration. The surface coated fly ash particles were incorporated as filler in recycled polypropylene (RPP) matrix composites by melt mixing in 1:1 weight ratio. The composites were tested for their flexural properties, impact behaviour, dynamic mechanical properties and fracture surface analysis. Increase in flexural strength, modulus and impact strength was observed in the coated FA/RPP composites. 1wt % PA coated FA/RPP composites showed great increase in flexural strength. In 1 wt% SA treated FA/RPP (RFASA1) composites highest shift in glass transition to a higher temperature were found. Fracture surface analysis revealed efficient filler matrix interactions in the SA and PA treated FA/RPP composites. Thus, green, renewable, inexpensive chemicals like stearic and palmitic acid was found to be an effective coupling agent in FA/RPP composites. © (2013) Trans Tech Publications, Switzerland.