<p>The danger of operational hydrogen damage to various structures, chemical reactors and pipelines lies in the fact that cracks appear suddenly, without prior noticeable plastic deformations of material. This makes it difficult to diagnose the pre-emergency condition in a timely manner. So, it is important to understand the mechanism of hydrogen-induced changes in the stress–strain state of metals. Studies were conducted on 20 samples of tube steel after varying durations of hydrogen charging. The concentration of accumulated hydrogen was measured. The samples were subjected to mechanical tests, and microstructural analysis of the cross-sectional metallographic specimens was performed. It was found that hydrogen charging results in the formation of voids within ferritic grains, which, as hydrogen accumulates, enlarge and merge, forming a network of microcracks along the grain boundaries. Additionally, hydrogen hardening of the samples was observed. A description of the hardening mechanism based on continuum mechanics approach is proposed. This involves solving the problem of determining the stress–strain state of elastic–plastic material containing hydrogen-induced pores. It is shown that the growth of pores leads to formation of extensive areas of plastic deformations and compressive stresses. This allows to explain the main experimental results without involving special mechanical models of hydrogen embrittlement.</p>