Chemically treated oil palm empty fruit bunches fiber (OPEFB) reinforced polyvinyl alcohol (PVA) biocomposites were prepared using solution casting technique. This paper focused on the effect of chemical treatments on mechanical, physical and thermal properties of PVA/OPEFB composites. The chemically treated fibers are characterized by universal tensile tester, X-ray diffraction (XRD), differential scanning calorimetric (DSC), and thermogravimetric analysis (TGA). The tensile strength and tensile modulus of the composites were found to be increased after chemical treatment was done on OPEFB fibers. XRD analysis showed that the crystallinity of fiber increase after different stage of treatment. TGA indicated that there was slight increase of the thermal stability for alkali + silane treated OPEFB fibers. In summary, the chemical treated OPEFB fibre has successfully improved the mechanical and thermal properties of PVA/OPEFB composite.