The micropore structure of xerogels of tin dioxide prepared by precipitatio
n is studied by the physical adsorption of N-2, O-2, and H-2 at -195.6 degr
ees C. The parameters of the microstructure as a whole depend on the adsorb
ate. The specific surface area of supermicropores measured by the oxygen ad
sorption exceeds that measured by nitrogen adsorption, and the extent of ex
cess increases linearly with an increase in the supermicropore volume. The
samples of tin dioxides have molecular-sieve properties, but they do not co
ntain ultramicropores measurable by the adsorption of molecular hydrogen.