Abstract: For a process for producing high-purity liquids, particularly liquid chemicals, by distillation it is proposed that the liquid to be purified (1) is heated by microwave radiation (5) preferably in the uppermost layers. To implement this process a device with a liquid container (3), with a heat source (5) acting on the liquid container and with a condensation device (8, 9) connected to the liquid container is proposed, which is distinguished in that the heat source (5) in the form of a microwave radiation source is arranged above the liquid to be purified (1) in such a way that preferably the uppermost layers of the liquid (1) are heated.