The synthesis of ethyl tert-butyl ether (ETBE) from a liquid phase reaction between ethanol (EtOH) ethyl and tert-butyl alcohol (TBA) in pervaporation membrane reactors (PVMRs) is discussed in this paper. Three modes of PVMR operation; semi-batch reactor (SBR), continuous stirred tank reactor (CSTR) and plug flow reactor (PFR) were modeled using kinetic parameters of the synthesis over beta-zeolite and permeability data for a polyvinyl alcohol (PVA) membrane from our previous work. Good agreement between experimental and simulation results for the SBR mode was obtained. The study focused on comparing PVMR performances between two modes of continuous flow operation for various operating parameters, i.e. ratio of catalyst weight to total molar feed rate (phi), ratio of membrane area to catalyst weight (delta), operating temperature and feed composition. It was found that the CSTR mode shows superior performance to the PFR mode only within some ranges of operating conditions. To obtain high ETBE yields, it is best to operate the PVMRs at low temperature with a high ratio of membrane area to catalyst weight (delta) and with the feed ratio of EtOH and TBA at the stoichiometric value or slightly higher. (C) 2003 Elsevier Science B.V. All rights reserved.