Synthesis of ethyl tert-butyl ether (ETBE) from the reaction between ethanol (EtOH) and tert-butyl alcohol (TEA) in the presence of different acid catalysts (KHSO4, NaHSO4, H2SO4, and Amberlyst 15) was investigated at low alcohol grade (mixture of 80 mol % water). Potassium hydrogen sulfate (KHSO4) showed the highest selectivity among the tested catalysts. Other catalysts caused the dehydration of TEA into water (H2O) and isobutene (IB). In the top of the reactive distillation column with total reflux, the condensate was split into two layers. The upper layer contained ETBE with a more than 60 mole fraction.