Abstract Many materials display a tendency to embrittle when subjected to a hydrogen environment. This behavior is extremely material specific and there is no reliable method for the prediction of embrittlement in previously untested materials. It is therefore necessary to experimentally determine the effects of hydrogen on materials which may experience such an environment during their service life. Inconel 718 has many applications in the aerospace industry and as a result may encounter a high partial pressure hydrogen environment. In this study, fractured Inconcel 718 tensile samples were examined in a scanning electron microscope to determine the effects of atmosphere on their fracture surfaces. Two base metal and two weld specimens were examined, one of each tested in 6.9 MPa helium or hydrogen atmospheres at room temperature. No evidence of embrittlement was noted for the base metal samples, while the weld samples were slightly embrittled. The effect was minor, however and the fracture mode in all four cases was ductile microvoid coalescence.