Abstract: The invention concerns a process for the isomerization of humulon in a carbon dioxide-hops extract and a process for the isolation of isohumulon from the isomerized carbon dioxide-hops extract. Aluminium or an aluminium compound, preferably aluminium trioxide is added to the carbon dioxide-hops extract in such a concentration that the mole ratio of aluminium: alpha acid (alpha humulon) amounts to from 1:0.1 to 1:6. The mixture is then treated with high alkali hydroxide concentration at a temperature of from 80.degree. to 160.degree. C.Isohumulon is obtained from the extract by adding so much tempered water that the isohumulon share amounts to 1 to 10% and the temperature is reduced to 40.degree. to 45.degree. C., and after further cooling to room temperature, the alkali isohumulons are purified from the other components in conventional manner and optionally are transformed in the conventional way into isohumulons.