To understand hydrogen behavior in V and V based alloys, static and dynamic hydrogen chargings were carried out for unirradiated and irradiated V and V-4Cr-4Ti. Hydrogen can be trapped by lattice defects, dislocations, vacancies and voids, which are effective up to 500 °C. Unexpected softening occurred at low levels of hydrogen, and hardening occurred at high levels. Alloying elements intensified the hardening, which are seen as general phenomena in V and V based alloys. A significant effect was seen for dynamic charging, which was attributed to fast diffusion and interactions with mobile dislocations.