Abstract Composites of polypropylene (PP) and alkali extracted steam-exploded Acacia mangium wood fiber (AEF) were prepared. The fiber was grafted with maleated polypropylene (MAPP), either Epolene E-43 or Epolene G-3003. Their performance as a compatibilizing agent was compared. Treated fibers were characterized with SEM, ESCA, and FTIR. SEM and ESCA showed the presence of both MAPPs at the fiber surfaces. FTIR spectroscopy was unable to detect ester links between MAPP and AEF. All mechanical properties were improved with the incorporation of the treated fibers due to improved fiber dispersion and fiber/matrix adhesion as revealed by optical and scanning electron micrographs. As a compatibilizer, Epolene E43 performed better than E polene G-3003.