A significant number of failures encountered in high-pressure steam boilers of thermal electric power stations are caused by damage of the tubes of the steam superheaters, which are made of 20, 12Kh1MF, 12Kh2MFSR and 12Kh18N10T steels. A statistical analysis made by the authors determined that a large number of the failures result from the action of hydrogen on the tubes. In this paper, the mechanisms of hydrogen diffusion, corrosion crack propagation, and brittle failure for steam superheater tubes were analyzed. Hydrogen-related intergranular cracking and thermal fatigue were assessed for the tube steels. It was concluded that hydrogen had a significant effect on processes of crack origin and propagation both in the superheater and in the unheated tubes of the boilers.