The tribological experiments under circumstances of hydrodynamic and elastohydrodynamic lubrication, the immersion test in lubricating oil as well as the exposure test to the environment have been performed to elucidate the effect of hydrogen on soft and hardened surface layers. The occurrence of the effect of hydrogen tribosorption in lubricated frictional nodes has been confirmed. This effect proceeds at a different rate and in a different way for nitrided surface layers (and homologous layers), on the one hand, and for other soft or hardened surface layers on the other. The most probable mechanisms of the tribosorption for both the cases mentioned above have been presented and the significance of that phenomenon for the theory as well as for practical operation has been discussed.