Abstract: Nanocrystalline cerium dioxide is a promising material for biomedical applications due to its ability to perform the functions of various enzymes and inactivate free radicals. One of the ways to tune the physicochemical properties of nanoparticles and its biocatalytic activity is to modify the crystal lattice structure by means of doping with trivalent rare earth ions. Peroxidase, oxidase activity, and the ability to inactivate the hydroxyl radical by pure and doped maltodextrin-coated cerium dioxide nanoparticles are studied in the present paper. © Pleiades Publishing, Ltd. 2023. ISSN 1063-7788, Physics of Atomic Nuclei, 2023, Vol. 86, No. 11, pp. 2546–2550. Pleiades Publishing, Ltd., 2023.