Hydrogen in materials degrades mechanical properties, which is widely recognized as hydrogen embrittlement. To understand hydrogen embrittlement, it is necessary
to clarify the accumulation behavior of hydrogen under stress. The neutron radiography and neutron tomogra-phy techniques are applied to examine whether hydrogen
accumulation behavior can be visualized directly. Palladium specimens with and without hydrogen were prepared for the neutron imaging experiment under stress. Solute
hydrogen has caused distinct contrast change in both the neutron radiography and neutron tomography. Hydrogen distribution at a notch-tip in a loaded specimen has not
been visualized in the to-mographic cross-sectional images. It can be inferred that this is fundamentally attributable to low spatial resolution of the present imaging set-up,
and possibility to visualize hydrogen distribution due to loading is discussed.