Spherical micro-mesoporous submicron particles of amorphous silica with a specific surface area (SSA) up to 2050 m2/g, comparable with that of nanoporous carbon materials, have been synthesized. Particle structure and chemical composition variations were studied by the adsorption porosimetry, thermogravimetric analysis and IR spectroscopy methods at formation stages. Sequential elimination of various organic porogens forming the particles’ structure by washing and annealing in different ambients leading to pore opening and corresponding SSA growth were demonstrated. The distinctive feature of the developed post-treatment procedure is the stabilization of the fragile silica backbone due to the formation of a distributed network of surface silanol groups that maintain the achieved characteristics of high porosity.