We report here on our thermal and hydrothermal investigations comparing mesoporous gamma-Al2O3 membrane with single and double dopant membranes prepared by the sol-gel method. Improvements in the hydrothermal stability of mesoporous gamma-Al2O3 by transition (Ga3+) or rare-earth (La3+) cations are discussed, along with the effectiveness of double dopant (Ga3+-La3+). The amounts of Ga2O3 oxide used varied between 0.0 and 30 mol% and those of La2O3 between 6 and 15 mol%. The thermal and hydrothermal (up to 75% steam) stability of nine types of membranes fabricated on an asymmetric porous alpha-Al2O3 support by means of a dip-coating process was characterized by H-2 gas permeation at 500 degrees C. By conducting tests with wide variations in dopant concentrations, material characterizations, and gas permeance performance, we have been able to optimize the key parameters for hydrothermally stable systems.