are used the processing comprises the filtration of the hydrogenating catalysts and separation of the acidic catalyst by distillation the reaction mixture remaining after separation of the catalysts is processed by distillation and or extraction preferably by distillation where necessary the processing may also comprise a crystallization step in the case of cyclodehydration of hexitols dianhydrohexitols that have been formed are mostly separated by distillation and a mixture of monoanhydrohexitols remains in the distillation sump it is a surprising and therefore significant advantage of the process according to the invention that polymers are practically not formed the rate of formation is below 1 mole relative to converted polyol hence the reaction mixture which is free from catalysts and water can be utilized further immediately or after separation of distillable dianhydropolyols by distillation monoanhydropolyols in particular those consisting of hexitols are therefore valuable raw materials for various fields of application where hitherto the content of polymers was troublesome through the preferred use of a low carboxylic acid and a heterogeneous hydrogenating catalyst it is possible to recycle not only the hydrogenating catalyst but also the carboxylic acid after separation thereof by distillation when mineral acids were to be used hitherto elaborate measures were necessary to separate the salt arising as a result of neutralization of the acidic catalyst from the anhydropolyol reaction mixture finally by virtue of the combination according to the invention of an acid catalyst and a hydrogenating catalyst it is possible to employ noble metal catalysts of high stability a factor which has an advantageous.