Abstract: In the preparation of an alkylene glycol such as ethylene glycol by hydrolysis of the corresponding aliphatic acid ester, the improvement which comprises hydrolyzing the ester in a distillation column, taking to a condenser as overhead a vaporous mixture of water and aliphatic acid from the hydrolysis column, which immiscible stream is mixed with vapors of a water immiscible aliphatic ketone in the condenser, condensing the mixture and conducting the condensate to a settling tank where an upper ketone phase containing extracted aliphatic acid and a lower aqueous phase is formed, recycling the aqueous phase to the hydrolysis column, feeding the ketone phase to a distillation column where the ketone is distilled off and returned to the condenser, and separating essentially anhydrous aliphatic acid from the bottom of the distillation column.