Correct selection and application of materials is essential to ensure safety and economy in production, transportation and storage of hydrogen. There are several sources of materials challenges related to hydrogen. Established component producers may have limited experience in this specific field. Process developments may involve new process conditions with new demands on the materials. Further, new materials will be added to the engineering toolbox to be used. The behavior of these materials for hydrogen service may need additional documentation. Finally, focus on hydrogen susceptibility and hydrogen damages alone may take away awareness of other subjects as trace elements, by-products and change in raw materials, which may be of as high importance for safety and quality. This overview of challenges and recommendations is made with emphasis on water electrolysis.