Nanoscale and microscale HZSM-5 zeolite catalysts were prepared and characterized by using SEM, XRD, IR, TPD and modified Hammett indicator method. Their performances in the dehydration of bio-ethanol into ethylene were compared in a fixed-bed reactor at 240 degrees C under atmospheric pressure. The results show that nanoscale HZSM-5 zeolite catalyst exhibits better stability than microscale HZSM-5 zeolite catalyst When the 95(v) % bio-ethanol is used as the reactant, over nanoscale HZSM-5 catalyst, the conversion of bio-ethanol and the selectivity for ethylene almost keep constant during 630 h reaction, while over microscale HZSM-5 zeolite catalyst, the conversion of bio-ethanol decreases after 60 h reaction, in the case of the 45(v) % bio-ethanol employed as the feedstock, over nanoscale HZSM-5 catalyst, the conversion of bio-ethanol and the selectivity for ethylene almost keep constant during 320 h reaction, while over microscale HZSM-5 zeolite catalyst, both the conversion of bio-ethanol and the selectivity for ethylene decrease almost at the beginning of the reaction. (C) 2009 Elsevier B V All rights reserved.