Abstract 1. 1. The porous matrix structure of catalysts containing zeolite changes markedly on replacing the inter-micellar water in hydrogel spheres by isobutyl alcohol and isopropylbenzene, the specific surface remaining approximately constant while pore volume increases considerably. 2. 2. The relation which govern the physical structure formation of an amorphous matrix are the same for amorphous aluminosilicate and catalysts containing zeolite and independent of the type and amount of zeolite in the specimen.