Dehydration reaction of ethanol was investigated in a temperature range of 140-250 degrees C with three different heteropolyacid catalysts, namely tungstophosphoricacid (TPA), silicotungsticacid (STA) and molybdophosphoricacid (NIPA). Very high ethylene yields over 0.75 obtained at 250 degrees C with TPA was highly promising. At temperatures lower than 180 degrees C the main product was diethyl-ether. Presence of water vapor was shown to cause some decrease of catalyst activity. Results showing that product selectivities did not change much with the space time in the reactor indicated two parallel routes for the production of ethylene and DEE. Among the three HPA catalysts, the activity trend was obtained as STA > TPA > MPA. (c) 2007 Elsevier Ltd. All rights reserved.