AbstractThis study focuses on the extraction of nanocrystalline cellulose (NCC) from the dried stalk of Corchorus olitorius,commonly known as jute,using a combination of a microwave-assisted alkaline peroxide pulping process (AHP) and ultrasonication. Dried jute stalk powder was pretreated using sodium hydroxide under microwave irradiation for the removal of lignin. The partially delignified sample was bleached using 30% hydrogen peroxide solution. The resulting crude cellulose was hydrolyzed using ultrasonication in the presence of ionic liquid and sulfuric acid. The effect of hydrolyzing medium on the physicochemical characteristics of the extracted nanocellulose was investigated. The nanocrystalline cellulose (NCC) obtained after combined treatments was rod-like, with diameters of 10 to 15 nm and lengths of 92 to 105 nm. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction analysis (XRD) showed that some breakages of intramolecular hydrogen bonds and glycosidic bonds occurred during the hydrolysis reaction of pretreated biomass. Ultrasonication in the presence of an acid hydrolyzing medium most effectively accelerated these breakages in the long chain cellulose biopolymer, leading to the formation of nanocrystalline cellulose (NCC) with higher crystallinity.