Underground hydrogen storage in porous rocks is a promising method for large-scale energy storage. However, results for the geochemical reactivity of hydrogen with reservoir rocks are still rare, particularly for their potential effects on reservoir performance. Some minerals such as hematite, pyrite, and calcite can react with hydrogen under certain temperatures. These mineralogical transformations due to the presence of hydrogen may change the pore structure and affect the storage properties. In this study, we investigated the geochemical reactivity of hydrogen with Buntsandstein reservoir sandstones, collected from hydrocarbon wells at a depth of about 2.5 km. The experiments were performed at 100 °C under 150 bar for one month. Four different scenarios including dry hydrogen, dry air, synthetic saline fluid-saturated rocks with pure hydrogen and with pure helium were systematically compared to understand the reaction attributed to hydrogen instead of fluid-rock interactions or temperature effects. Permeability, porosity, magnetic susceptibility and fluid element concentration were measured before and after experiments to shed light on the potential reaction. The results indicate that no fundamental and substantial changes in the minerals were induced by hydrogen reaction under the simulated conditions. Magnetic susceptibility reveals that no magnetic minerals (e.g., magnetite) were formed. The slight variation of permeability and porosity is mainly due to fluid-rock interaction indicated by the changes in the fluid element concentration. Our results reveal that there is no risk of hydrogen loss and reservoir (Buntsandstein sandstone) performance reduction due to geochemical reactions of hydrogen under temperatures up to 100 °C.