Dual-phase hydrogen permeation membranes, consisting of protonic and electronic conducting phases, shows great potential for high purity hydrogen production due to its high stability in harsh applications. Hydrogen-ion conductive perovskite phases (e.g.Ā BaCe0.65Zr0.2Y0.15O3-Ī“) and electron conductive fluorite oxides (e.g.Ā Ce0.85Gd0.15O2-Ī“) are promising candidate for this biphasic hydrogen transport membrane. Mechanical properties (e.g. elastic modulus, hardness, fracture toughness) of the membranes are essential parameters regarding the reliability of subsequent applications. These parameters are closely related to microstructural features such as grain size, phase distribution and defects (e.g. pores and microcracks). However, these relationships are not yet fully understood. Therefore, in this thesis, the effects of grain size, phase distribution, pores and microcracks on mechanical properties are investigated forĀ BaCe0.65Zr0.2Y0.15O3-Ī“Ā andĀ BaCe0.65Zr0.2Y0.15O3-Ī“-Ce0.85Gd0.15O2-Ī“Ā membranes. Material preparation procedures (e.g. milling and sintering) are optimized to overcome the difficulty in material preparation. This PhD thesis use 6 Chapters to investigate from material synthesis to thermal-mechanical properties on the above mentioned materials. At the end, perspectives are givenĀ regarding the improvement of the materials for higher thermal-mechanical stability.