A model of the process of hydrogen diffusion over the crystal structure in solids is presented. A defect-free and defective structure are considered. This study is relevant for the process of hydrogen embrittlement, which can lead to premature destruction of the material. A hypothesis about the creation of a surface layer upon pre-charging a sample with hydrogen is considered, which is necessary for further study of the hydrogen desorption process. The effect of the surface layer on the extraction curves is studied, and the simulated extraction curves are compared with the experimental ones. The results obtained make it possible to better understand the interaction of hydrogen atoms with the structure of a solid.