Novel type of light heat-resistant polymer concretes was developed on the basis of oligooxyhydridesilmethylenesiloxysilan with hollow glass or ceramic microspheres. Adding hollow glass and ceramic microspheres being waste products from thermal power plants operating on solid fuels allowed developing reasonably priced materials and reducing potential environmental pollution. For optimization of production technology, the curing and molding conditions of materials were studied. According to impact strength changes, the optimal curing mode for the composites was at 480–515 K for 4.25–4.5 hours depending on the filler type and binder content. It was stated that used organic-silicon binder provided thermal resistance and high strength characteristics of the composite material. In comparison with traditional silicone resins, the compressive strength value of the developed materials increased by almost two times and the modulus of elasticity increased by almost an order of magnitude. Due to the interaction of aluminum hydroxide groups of ceramic microspheres with organosilicon polymer, Young’s modulus of the materials filled by ceramic microspheres was higher by 20–30 % than that of the concretes with glass microspheres. Consequently, enhanced physical and mechanical properties expand possibilities of using these materials under exposure of significant external static loads.