The influence of cyclic moisture loading and unloading on the material behavior and the mechanical properties of gamma-Al2O3 granules has been studied by uniaxial compression tests. For this purpose, the granules have been treated with two different types of moisture loading and unloading cycles. During treatment with wet air, the mechanical properties of granules decrease with increasing moisture content. On subsequent drying of granules in a drying chamber in order to achieve regeneration, the initial condition can only be partially restored. With increasing number of moisture loading and unloading cycles, a continuous decrease in the strength of granules takes place. Furthermore, a significant relationship between granule size and damage could be observed.