Abstract: Provided is a process for preparing tertiary butyl alcohol from isobutylene comprising reacting isobutylene or a hydrocarbon mixture containing isobutylene with an aqueous solution of an aliphatic carboxylic acid having from 1 to 6 carbon atoms in the presence of a solid, acidic ion-exchange resin as catalyst, to produce an aqueous reaction mixture of a major amount of tertiary butyl alcohol and a minor amount of the tertiary butyl ester of the carboxylic acid comprising the improved steps of:(1) subjecting said reaction mixture to distillation to remove unreacted isobutylene or hydrocarbon mixture therefrom;(2) supplying the treated reaction mixture of step (1) to a distillation column and passing water from the top to the bottom of said distillation column to remove said tertiary butyl ester of the carboxylic acid, wherein the amount of water used for removing the ester in step (2) is less than the sum of the amount of water used for converting said isobutylene into tertiary butyl alcohol and the amount of