Rapid fracture (or sudden fracture) of various wrought and weld metals in the environment have been observed during compact tension (CT) test in different laboratories. Hydrogen distribution throughout the metal has been proposed as the most possible mechanism to explain such a sudden or very rapid crack advance. This paper summarizes those findings and reports on controlled experiments designed to understand this phenomenon in cold-worked stainless steel and alloy 82/182 weld metal. SEM characterization of previous fractured specimens showed that rapid fracture usually produces ductile dimple fracture morphology although such fracture occurred at K values as low as 38 ksi/in. The effects of dissolved H2 and/or O2 concentration (threshold) K value the rate of change in K and water temperature on the occurrence of rapid fracture were investigated using CT specimens in high temperature water. The tests were designed to sustain stress corrosion crack (SCC) growth over sufficient time to allow hydrogen to permeate throughout the specimen then slowly increase K to intentionally reproduce the rapid fracture and evaluate the role of hydrogen on this behavior. The possibility of developing a specific protocol or guideline to evaluate this phenomenon in a fast and repeatable way was also evaluated.