The dynamic mechanical properties of wood flour (WF) reinforced recycled expanded polystyrene (r-EPS) composites were investigated as a function of the WF content and coupling agent used. With the incorporation of WF into the polystyrene the storage modulus (E') and loss modulus (E?) were found to increase and the mechanical damping (tan d) decreased. The use of coupling agents improved the storage modulus and reduced the damping peak values of the composites because of the improved WF/matrix interfacial adhesion. The height of the damping peaks was found to be dependent on the content of maleic anhydride groups and the weight average molecular weight (Mw) of the coupling agent used. Finally, the experimental results were compared with the theoretical predictions for tan d and the storage modulus. (c) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012