High temperature fuel cells of SOFC type as direct energy converter of chemical energy into electricity show a high potential to reduce considerably the specific energy consumption in different application fields. Of particular interest are advanced light-weight planar cells for electricity supplying systems in mobiles which consist at present development state in main parts of metals e. g. ferritic steels. These cells operate in a temperature range of about 800°C where oxidation and diffusion processes can be of detrimental effect on cell performance at least at the required long-term operation. Problem fields are in particular the diffusion of Cr-species from the interconnect or the casing into the electrolyte/cathode interface forming insulating phases and the mutual diffusion of substrate and anode material e. g. Fe and Cr from the ferrite into the anode and Ni from the anode into the ferrite which in both cases reduces performance and system lifetime. Protecting and intermediate layers, respectively, can reduce such effects considerably, but they should be dense and of high electronic conductivity and stability. Perovskite-type layers e. g. doped LaCrO₃ applied with adapted high-velocity DC-VPS promise to solve reliably such problems.