Reducing industrial slags and developing building materials on its basis is one of the priority areas for the development of the construction industry. The problem of obtaining cellular concrete from mineral wool production waste (lightweight geopolymers) is considered within the framework of the researches, the results of which are presented in the article. The research purpose was to establish the impact of composition of the raw material mixture and technological production features on the physical, mechanical and thermophysical properties of light geopolymers based on mineral wool production waste. Light geopolymers were obtained by preparing a mixture of ground slugs (specific surface is 400±20 m2/kg), alkaline activator (NaOH), water, a gas-forming additive (aluminum powder), fine aggregate and a water-holding additive. The resulting mixture was placed in the form without vibration. Molded products were steamed in order to accelerate hardening. The mobility of mortar mixtures was studied during the work, the average density, compressive strength, and thermal conductivity was studied for hardened samples. The compositions of lightweight geopolymers with an average density from 610 to 1,130 kg/m3, compressive strength from 1.7 to 5.4 MPa, and a thermal conductivity from 0.144 to 0.345 W/m∙°C were obtained. The application of the results will contribute to the expansion of the raw material base for obtaining light geopolymers, thereby reducing the amount of waste generated during the mineral wool production. The developed materials can be used for the construction of walling, and also as the insulation of the roof and floor of industrial and civil facilities.