Nanoseeds of BZSM-5 zeolite with a narrow particle size distribution of 100200?nm were successfully prepared under mild hydrothermal conditions. Thin and oriented BZSM-5 membranes of 34 mu m, prepared at low temperature, were manufactured and examined for the separation of 5?wt-% ethanol/water mixtures. Separation factor and flux were 13.93 and 1.11?kg?m2h1, respectively. The temperature of synthesis showed a remarkable influence on the morphology, crystal orientation and separation performance of the membranes. The thinner a,b-oriented membrane showed a higher separation performance than the thicker h0h-oriented one.