Hydrogen will play a key role in the decarbonization of steel manufacturing and other high temperature processes in the industry replacing carbon as reactant for reduction processes and fossil fuels. Hydrogen can attack oxide based refractories by creating volatile phases through reduction and weakening and destroying refractory linings over time. The resistance of oxides against such attack depends on their thermodynamic stability and the process conditions in the application. Temperature, process gas composition and pressure, and gas velocity are important factors. Synthetic alumina based materials are known for their higher resistance against hydrogen attack and therefore are applied for example as refractory linings in petrochemical processes. However, new hydrogen applications such as reducing agent for direct reduced iron or as fuel in industrial combustion processes will involve higher hydrogen concentrations and process temperatures when compared to existing applications in the petrochemical industry. Therefore research is needed on resistance of alumina-based refractories under these new conditions. The paper discusses new results for hydrogen resistance of synthetic alumina based castables with different cement contents, hydratable alumina and matrix approaches including reactive alumina and silica fume. Testing was done with pure hydrogen at 1150 and 1400 °C for 200 hours and measuring weight and strength loss.