To meet the global energy crises arising from the ongoing depletion of fossil fuels new methods and materials for energy production have to be developed. In this context fuel cells may play an important role due to their high efficiency and low emissions. The main focus of this study is to characterise a cobalt-based electroceramics which is considered as a promising material for the application as cathode in solid oxide fuel cells (SOFC). Current research efforts are directed to reduce the operating temperatures of SOFCs to the intermediate temperate regime of 600-800°C. Within this work the mixed conducting material structure La0.5Sr0.5CoO3-d is studied which shows perovskite-structure and a pronounced electronic conductivity and high surface exchange coefficients for oxygen. Such material parameters are important to assess the performance of a potential SOFC-cathode material and have been determined by the van der Pauw method and the conductivity relaxation technique. Investigations were carried out at temperatures and oxygen partial pressures relevant for the application as SOFC-cathode material. Experimental results are presented and discussed in this work and a comparison with the literature including interpretation is provided.