Nanocrystalline cellulose extracted from oil palm empty fruit bunch fiber through Sulphuric acid hydrolysis process. Surface functionalization of nanocrystalline cellulose using TEMPO-mediated oxidation. Nanocrystalline cellulose reinforced PLA/PHBV bionanocomposites films were prepared by solution casting techniques. Improvement of oxygen barrier was observed in nanocrystalline cellulose reinforced bionanocomposite films. Nanocrystalline cellulose increased the mechanical properties of bionanocomposite film.