A study of open literature was performed to determine the effects of high hydrogen purity and gas pressure (in the range of 700-1000 bar) on the hydrogen embrittlement of several metallic materials. A particular focus was given to carbon, low-alloy, and stainless steels, but information on embrittlement of aluminum and copper was included in the study. Additionally, the most common test methods were studied, and results from similar tests are presented in a manner so as to simplify comparisons of materials. Finally, suggestions are provided for future testing necessary to ensure the safety of hydrogen storage at 700 bar.