Adsorption of H₂S and CH₃SH on SiO₂, Al₂O₃, TiO₂, and ZrO₂ and the resulting changes of surface acidity were studied by means of IR spectroscopy using CO (at 77 K) and 2,6-dimethylpyridine (DMP) (at 300 K) as probe molecules. Both H₂S and CH₃SH form H-bond with surface OH groups of all the adsorbents. For silica it is the only way of adsorption, while coordination as well as dissociative adsorption leading to formation of OH groups and molecular water occur on the three other oxides. Two types of induced Brønsted acidity were established, according to the mechanism of adsorption of the sulfur-containing compound. In the presence of large amount of sulfur-containing molecules, a reversible increase of the OH group acidity occurs, as revealed by the frequency shifts of the bands of H-bonded CO molecules and of perturbed OH groups on increasing H₂S coverage, or by the increased intensity of protonated DMP in the presence of H₂S. This effect is explained by the interaction of molecular H₂S with oxygen atom of the OH group. For Al₂O₃, TiO₂, and ZrO₂, dissociative adsorption of H₂S and CH₃SH results in the appearance of new OH groups that account for an irreversible, at least at 300 K, increase of Brønsted acidity revealed by higher intensity of corresponding bands of H-bonded CO and of protonated 2,6-dimethylpyridine. These new OH groups correspond to the most acidic of those that normally exist at the surface of the considered metal oxides. In no case the S-H groups of adsorbed molecules or surface SH groups formed by dissociation could account for the observed Brønsted acidity increase.