Abstract: Due to the pollution of groundwater by methyl tert -butyl ether(MTBE),the United States government in March 2000 interdicted this ether.Ethyl tert -butyl ether (ETBE) outranks MTBE as an octane enhancer since it shows the lower blending Reid vapor pressure, higher octane value and so on.For this reason,the research about the synthesis of ETBE had gained significant momentum over the past few years.In our previous work,the synthesis of ETBE from ethanol(EtOH) and tert -butyl alcohol (TBA) was studied by using cation exchange resin as catalyst via reaction, reactive distillation, reaction with pervaporation.In this work, catalytic reactive distillation coupled with pervaporation is restudied for the synthesis of ethyl tert -butyl ether from EtOH and TBA.A mathematical model for this combined process is developed.The model incorporates complex reaction kinetics,vapor-liquid non-idealities, distillation and pervaporation process.The rapid solution for this model can be obtained by modified overrelexation method.Simulation results are in good agreements with the experimental results.Some operating parameters are also optimized.