In the process of extracting cellulose from rice stems using the sodium method, the effect of the alkali solution concentration was studied and microcrystalline cellulose was synthesized from the obtained cellulose. Structural and morphological characteristics of rice cellulose fibers were studied. The average length and width of cellulose fibers, their fractional composition and shape factor were determined on an automatic Fiber Tester analyzer. The structure of the obtained cellulose and MCS was determined by X-ray diffraction, IR spectroscopy, adsorption isotherm on a McBen-Bakr device, saturated adsorption of polar and non-polar molecules. The influence of the synthesis time of cellulose from rice stems and MCS from the obtained cellulose on the physicochemical properties was studied. MCC yield best at 45 min hydrolysis Aerogel was extremely porous, crystallinity reduced after processing, successful synthesis of MCC and aerogel, properties confirmed by XRD, IR, adsorption and promising for industrial use.