A microporous zirconia membrane with hydrogen permeance about 5 x 10(-8) mol.m(-2).s(-1).Pa-1, H-2/CO2 permselectivity of ca. 14, and excellent hydrothermal stability under steam pressure of 100 kPa was fabricated via polymeric sol-gel process. The effect of calcination temperature on single gas permeance of sol-gel derived zirconia membranes was investigated. Zirconia membranes calcined at 350 degrees C and 400 degrees C showed similar single gas permeance, with permselectivities of hydrogen towards other gases, such as oxygen, nitrogen, methane, and sulfur hexafluoride, around Knudsen values. A much lower CO2 permeance (3.7 x 10(-9) mol.m(-2).s(-1).Pa-1) was observed due to the interaction between CO2 molecules and pore wall of membrane. Higher calcination temperature, 500 degrees C, led to the formation of mesoporous structure and, hence, the membrane lost its molecular sieving property towards hydrogen and carbon dioxide. The stability of zirconia membrane in the presence of hot steam was also investigated. Exposed to 100 kPa steam for 400 h, the membrane performance kept unchanged in comparison with freshly prepared one, with hydrogen and carbon dioxide permeances of 4.7 x 10(-8) and -3 x 10(-9) mol.m(-2).s(-1).Pa-1, respectively. Both H-2 and CO2 permeances of the zirconia membrane decreased with exposure time to 100 kPa steam. With a total exposure time of 1250 h, the membrane presented hydrogen permeance of 2.4 x 10(-8) mol.m(-2).s(-1).Pa-1 and H-2/CO2 permselectivity of 28, indicating that the membrane retains its microporous structure. (C) 2015 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.