Tetracyanocomplex clathrates and their changes caused by heating were studied. The intermediates formed were characterized by IR and UV-VIS spectroscopy. Elemental analysis and XRD patterns were also used. For the visualisation of changes occurring on the surface and the distribution of metallic elements therein were studied by electron microscopy and EDX. The extent of the non-stoichiometric changes introduced by the topochemical course of the degradation reactions was correlated with the measured electrical values.