Mesoporous Al2O3 was prepared by a sol-gel method with doping different amount of LaCl3. The proton conductivity of mesoporous Al2O3 increased with increasing the doping concentration up to the optimum doping, 0.1 Cl/Al mole ratio. The surface acidities of different samples were investigated by NH3-TPD method, The change trends of surface acidity are consistent with that of proton conductivity. It indicates that the proton conductivity of mesoporous Al2O3 can be increased by enhancing its surface acidity via the chloride doping. (C) 2010 Elsevier B.V. All rights reserved.