Influence of the temperature of aluminum oxide micropowder modification with Al 2 O 3 nanopowders in the interval 200-1000°С on the granulometric composition, diffusion reflection spectra in the wavelength range 360-2100 nm, and integral solar radiation absorption coefficient of coatings fabricated on the basis of these powders as well as on changes of these parameters upon exposure to electrons is investigated. It is demonstrated that with increase in the modification temperature, the average powder particle size decreases, the negative action is intensified, and the radiation resistance of coatings increases.