Sol-gel derived silica membranes have shown large selective permeance for hydrogen at high temperature, but the stability in hydrothermal conditions is insufficient. It is considered necessary to improve their stability against hydrothermal conditions such as the LNG reforming process, which contain high concentrations of water vapor. In this work the effects of zirconium contents in silica-zirconia composite membranes on the hydrogen permeation performance were studied. A silica-zirconia membrane with molar ratio 9/1 shows a H-2 permeance of 1 X 10(-5) m(3) (STP) m(-2) s(-1) kPa(-1) and H-2/N-2 selectivity of more than 100. An increase in zirconia content causes a decrease in the H-2 permeance and the permeability ratio of H-2/N-2. The activation energy of H-2 and Iie permeation increase with an increase in zirconia content, suggesting membrane densification with an increase in zirconia content.