Electrode materials for devices such as solid oxide fuel cells must be catalytically active and good ionic and electronic conductors. In particular, recent work in our laboratories has shown that A-site deficient perovskite oxides exhibit excellent performance when used in devices such as solid oxide fuel cells. Two contrasting methods for the synthesis of such perovskites are a conventional ‘exsolution’ method, or a ‘dissolution-exsolution' method. The aim of this experiment is to probe the mechanism of the ‘dissolution-exsolution’ processes in-situ which will enable us to better understand the structural and chemical changes and will enable us to optimise both our synthetic procedures and crystal chemistry to further optimise the electrochemical performance of such perovskites in a variety of devices.