Pure-silica MFI zeolite (silicalite-1) membranes exhibit great potential in the separation of an ethanol/water mixtures. For synthesis of silicalite membranes, however, conventional supports such as alpha-Al2O3 and mullite have aluminum element leaching out and entering into a zeolite structure, which would reduce the hydrophobicity of the zeolite layer and thus affect the separation performance for ethanol selectivity. In this paper, we prepared silicalite membranes on hollow fiber substrates fabricated with yttria stabilized zirconia (YSZ) without aluminum. The influence of seed size, synthesis parameters, and substrates was investigated. The as-synthesized membranes were characterized by scanning electron microscopy (SEM), electron probe microanalyzer (EPMA), infrared spectrum analysis (IR), and X-ray diffraction (XRD). A thin MFI zeolite layer with a thickness of about 3 mu m could be formed on the support, which exhibited highly selective to ethanol over water. A high flux of 7.4 kg m(-2) h(-1) with the separation factor (ethanol/water) of 47 was achieved on the as-made membrane for separating 5 wt % ethanol/water at 60 degrees C.