The impacts of the hydrolysis treatments on the crystallinity index of treated products can be investigated from the X-ray diffractograms. The crystallinities of native cellulose and isolated nanocellulose products were characterized by X-ray diffraction (XRD) study. The XRD patterns of the specimens were obtained from an X-ray diffractometer (PANalytical Empyrean) with a Cu-Kα radiation source which operated at 40 mA and 40 kV. The diffractograms were recorded from 5° to 60°. Crystallinity index (CrI) of samples was calculated by the peak deconvolution method as described by . Generally, the crystallinity of samples was calculated by dividing the total peak area of all the crystalline peaks by the total peak of all non-crystalline plus crystalline peaks according to the Equation (5): (5)CrI (%)AcAc+An×100 where Ac and Am are the area under the crystalline and non-crystalline regions, respectively.