Abstract: A method and system for probing a volume of material by detecting local conductivity in the material using microwave radiation. The probed volume of material is exposed to microwave radiation of a wavelength selected to excite the carriers of electrical current and induce localized heating in regions of the volume of material which is an electronic material or a device. A thermographic imaging system detects size and distribution of the locally heated regions, and a processing system determines a selected property of the material by analyzing the size and distribution of the locally heated regions. The thermographic imaging system can be an infra-red imaging system which detects infra-red radiation emitted from the locally heated region, or it can be a system which deposits a thermally sensitive film onto a surface of the material and detects thermally induced changes in the deposited film caused by the transferred heat.