In autumn 2013, the industrial partner Hexis has started the pilot market launch of the combined fuel cell heating device Galileo 1000 N. Keeping the stack power degradation as low as possible while achieving stack lifetimes above 40’000 h was one of the major challenges. Therefore, the focus of the SOF-CH ESC project was on determining and reducing the main causes of degradation, in order to increase the lifetime of SOFCs.One of the work packages of the project aimed at achieving a better understanding of the degradation mechanism which reduces the ionic conductivity of the electrolyte. Using x-ray diffraction (XRD) methods, procedures were developed to investigate ageing in-situ and ex-situ, as well as spatially resolved, and to improve understanding of this process.