Temperature-programmed desorption using hydrocarbons (propane, propylene, isobutane, and isobutene) was applied to investigate the base strength of solid bases. Among the used probe molecules, propylene showed acid–base interaction with base sites on solid bases. The activation energies of propylene desorption for CaO, MgO, and Al₂O₃–MgO prepared by thermal decomposition of hydrotalcite were 53, 41, and 34 kJ mol^–1, respectively. Our results show that propylene is superior as the probe molecule for base site analysis.