BaZrO3 and BaCeO3-based materials have potential application as electrolytes for solid oxide fuel cells (SOFCs) and solid oxide electrolizer cells (SOECs) due to lower operating temperatures and higher efficiencies with respect to commercial electrolytes (CGO, LSGM, YSZ). Also, these materials have been proposed as isotopic separation membranes and water sensors. The understanding of protonic defect mobilities and lattice distortions are crucial to develop materials with high protonic conduction.Thus, information about proton diffusion coefficient and average proton jumping length, by QENS under wet (H2O vapour) and dry atmospheres for the BaCe0.4Zr0.4Y0.2O3-d perovskite would help us to understand proton dynamics, between 298 and 1073 K. The combination of H-dynamics with in situ structural determinations would give us insights about diffusion mechanism of protons and how it is affected by structural changes. We will compare this information with EIS measurements in order to separate H-ion from O-ion transport.