A new variant of the hydrothermal treatment of silica in hydrogel-xerogel form is presented. This variant combines the processes typical for hydrothermal treatment either of hydrogels or of xerogels and typical processes for the drying of a gel in an autoclave. This method makes it possible to regulate specific surface area and pore diameter over a wide range and thus to synthesize high-porosity adsorbents characterized by sufficiently high mechanical strength. The method described here is useful for preparation of spherical and microspherical particles of silica gels for which the starting gels are characterized by smaller porosity and higher mechanical strength.