An experimental method and a corresponding setup have been developed for investigation of impedance spectra and other electrical properties of solid materials in radio frequencies from 300 kHz to 3000 MHz and temperature range 300-1200 K. The method is based on the measurement of S-parameters for a 2-port network made of a coaxial waveguide and a sample, inserted in the gap of a central conductor. Experimental setup is based on measuring device - Agilent E5062A network analyzer and is controlled by an application developed on base of Matlab environment. A sample holding coaxial waveguide is made of platinum covered refractory ceramics, which distinguishes itself by low thermal expansion: this enables accurate impedance measurement at high temperatures. (C) 2010 Elsevier B.V. All rights reserved.