Geopolymerization is an emerging technology which utilizes solid aluminosilicate raw materials that are easily soluble in caustic solutions, in order to produce inorganic polymers with excellent physical, mechanical and thermal properties. In this paper is demonstrated the ability of geopolymerization technology for production of thermal insulating foamy inorganic polymers utilizing as solid raw material ultrafine perlite which is a by-product from comminution and sizing operations of perlite exploitation. Hydrogen peroxide is used as a chemical blowing agent for the foaming of inorganic polymers. The effect of addition of the blowing agent on the thermophysical properties of thermal insulating materials is demonstrated and these properties are compared with the ones of the commercial thermal insulating materials indicating the high potentiality for the development of this new family of inorganic polymeric materials. (C) 2010 Elsevier Ltd. All rights reserved.