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. Finally, suggestions are provided for future testing necessary to ensure the safety of hydrogen storage at 700 bar. (C) 2010 Published by Elsevier Ltd on behalf of Professor T. Nejat Veziroglu.