In the present study, the mixtures of bis(triethoxysilyl)ethane (BTESE) and methyltriethoxysilane (MTES) were proposed to design highly selective hybrid silica membranes for gas separation by the sol-gel method. The role of MTES in the hybrid membranes was investigated by changing the ratio of the two precursors. The membrane derived from mixture of 1 BTESE and 3 MTES exhibited the highest H-2 and CO2 permeance with 7.99 x 10(-7) mol m(-2) S-1 Pa-1 and 3.53 x 10(-7) mol M-2 s(-1) Pa-1, respectively. In contrast, the superior selectivity was achieved on the membrane derived from mixture of 1 BTESE and 2 MTES, in which the H-2/N-2, H-2/CH4, CO2/N-2, and CO2/CH4 were found to be 64.4, 73.6, 28.5, and 32.6, respectively, which indicated that the structures of BTESE-MTES hybrid membranes can be adjusted by tuning the ratios of MTES to BTESE. Moreover, the membranes also performed well in the binary-component mixture gases and high-temperature test.