Abstract
Hydrogen embrittlement and its related phenomena in pure titanium and titanium alloys are introduced. Hydrogen embrittlement in titanium is closely related to the hydride formation. In case that a considerable amount of hydride forms in the materials, embrittlement can be confirmed by high strain rate testing using notched specimens such as impact testing. In more static low strain rate testing such as sustained load cracking testing, it is considered that hydrogen embrittlement appears due to hydrogen diffusion to crack tips and hydride formation there during testing. In beta type titanium alloys containing a high quantity of Mo and/or V, hydrides formation is not easy and they have high resistance against hydrogen embrittlement.