Abstract: A process is provided for selective etherification of iC.sub.4 =with EtOH to form ETBE in a distillation column reactor containing a fixed bed acid cation exchange resin as a catalytic distillation structure in a reaction distillation zone combined with a straight pass fixed bed reactor. A C.sub.4 feed containing isobutene is mixed with the total liquid downflow from the catalytic distillation reactor and passed to a straight pass fixed bed reactor, where up to about 85% of the isobutene is reacted with ethanol in the distillation column reactor effluent. This stream is returned to the distillation column reactor at a point below where the liquid downflow is withdrawn and then fractionated on conventional trays to remove ETBE as a bottom product.