n this thesis, clay composite materials were examined with regard to the penetration of microwave radiation in the frequency range between 1.5 and 6.0 GHz, which is used for mobile telephony (2G - 5G). Nanomaterials (fly ash, titanium dioxide of different particle sizes and phases, zinc ferrite, iron(III) oxide, antimony(III) tin(IV) oxide and multi-walled carbon nanotubes) added to clay, as the basic material, were characterized by physical and chemical methods (specific surface area, thermal properties, phase composition, morphology, chemical and mineralogical composition). Tests of the penetration of microwave radiation with a spectral analyzer were carried out on fired discs with a diameter of 15 cm, which were made as two-component clay composites having 1, 2, 3, 5 and 10 % of the mentioned nanomaterials. According to the obtained results, three-component mixtures (clay, titanium dioxide with fly ash and antimony tin oxide) were prepared and tested. The thermal conductivity of all two-component and three-component composites was determined. In order to test the applicability in construction, solid bricks were made from the three-component mixtures and their water absorption and compressive strength were determined. The results show that the addition of investigated nanomaterials to clay significantly reduces penetration in the area of microwave radiation, and at the same time improves the tested physical-mechanical properties.