Sr1-xBaxCe0.5Zr0.35Y0.1Sm0.05O3-&; (SrBCZYSm) where x = 0,0 - 0.9 are promising as intermediate temperature solid oxide fuel cell electrolyte. PXRD reveals that all of the samples show cubic symmetry. Impedance studies confirm that the conductivity is dominated by protons at intermediate temperature and increases with increasing the proportion of Ba in the structure. Fuel cell test observed peak power densities of 695 mW/cm2 at 600 °C, which is highest performance until now for x=0.9.This proposal requests 4 days beamtime on Polaris to perform an in-situ experiment studying ionic (proton) conductivity during the diffraction experiments as a function of temperature on SrBCZYSm in dry and humid atmosphere. The outcome of this in-situ experiment will provide us a deeper understanding of the structure-property relationships within these types of proton conducting samples.