The results of calculated and experimental studies of the influence of some parameters (the temperature and time of tritiation and aging, the cooling rate after tritiation) on the helium-3 concentration in metals are given. It has been experimentally found that the hydrogen concentration in [null]3 mm samples of 12Cr18Ni10Ti steel, which were saturated with hydrogen at 773 K and 50 MPa, makes up ~ 0.6 of the equilibrium hydrogen concentration immediately after cooling to room temperature and ~ 0.5 after 5000-hour aging.