Devices in nano-electronics frequently consist of complex two- or three-dimensional structures with complex chemistries. A detailed characterisation thus requires not only a thorough structural characterisation, but also a highly resolved characterisation of elemental distributions. Energy filtering transmission electron microscopy is a very valuable tool for such investigations, as will be demonstrated on the basis of three different examples: a novel design of a nanoscale field effect transistor, a model design for a magnetic random access memory cell and magnetic core shell nanoparticles suitable for future nanoscale memory.