A synthetic procedure for bacterial nanocellulose (BNC) from oat hulls is suggested herein. This procedure involves several stages: chemical pretreatment of feedstock followed by successive treatment with dilute sodium hydroxide and nitric acid; enzymatic hydrolysis of pulp; synthesis of BNC by the Мedusomyces gisevii Sa-12microorganism on a nutrient broth obtained from enzymatic hydrolyzate; and BNC washing. The yield of dry BNC was 4.8% and the degree of polymerization was 2010. The IR spectroscopy confirmed the cellulose chemical purity, the TGA analysis confirmed the typical decomposition of the polymer, and the SEM analysis showed that BNC had an intrinsic nanoscale network structure. X-ray diffraction revealed that the BNC had 99% triclinic Iα allomorph and 88% crystallinity index.