In order to reduce the greenhouse effect, research on fuel cells and particularly on SOFCs has been extensively developed as the only produced waste is water. In situ structural characterisation on SOFC materials have been progressively developed over the last years, leading recently to studies close to real operating conditions, under an electric load at high temperature but under vacuum. The studies by XPS clearly showed cation migration between the electrode and the electrolyte that can lead to material degradation. We would like to perform similar experiments with neutron diffraction but under closer real operating conditions (under air) on other promising materials (LSCF/CPO) to look at their behaviour under an electric load.