As a result of its melting point of 2996 °C tantalum belongs to the group of the refractory metals. Tantalum is characterised by an outstanding chemical and thermal resistance as well as a formation of a very stable oxide film, created by anodising. Hence tantalum is often used for the production of solid electrolyte capacitors in the electronic industry. By the usage of fine tantalum powder, which is sintered to porous anodes, the ratio of capacity/volume can be increased, wherefore these capacitors are especially suitable for mobile electronics. For the inlet of the electric current into the condenser a tantalum wire is pressed and sintered into the anode. During sintering at high temperatures, impurities, especially oxygen, diffuse from the tantalum powder into the wire. By the interstitial storage of oxygen, tantalum loses substantial ductility, which frequently leads to wire fracture in the further production or application of condensers. In order to prevent diffusion of oxygen and the subsequent negative effects on application, the wire is provided with a self-reducing surface layer. The aim of this diploma thesis was the characterisation of such a layer. Therefore, metallographic investigations, bending- and pull-out-tests were carried out. Furthermore, X-ray diffraction patterns were recorded, and the electrical conductivity as well as the leakage-current were determined.