A process is provided for increasing the yield in the preparation of polyhydric alcohols obtained from methylolated alkanals by hydrogenation, wherein derivatives of these alcohols are decomposed by adding 5 ppm to 1% by weight, preferably 100 to 1000 ppm, of a suitable acid to an anhydrous mixture containing these derivatives, heating the mixture to temperatures of 100 to 300° C. and then separating off the polyhydric alcohol by distillation. This process makes it possible simply and efficiently to decompose compounds which boil above the polyhydric alcohol and are unwanted by-products of its synthesis.