Abstract Hydrogen isotopes from the Water Detritiation System (WDS) developed at the Tritium Laboratory Karlsruhe (TLK) are fed to a cryogenic distillation (CD) column. In order to purify this gas a permeator of 1 m 2 membrane area was found to be necessary. Technical requirements, regulations of the European Union and the TLK safety philosophy demanded that the component had to be designed and manufactured in accordance to the “Technical Terms of Delivery and Acceptance” for tritium primary systems in the Tritium Laboratory Karlsruhe and in conformity to the European Pressure Equipment Directive (PED). Since there was no response to the call for tender from industrial partners, the permeator was manufactured at the main workshop of the Forschungszentrum Karlsruhe (FZK). Acceptance tests and commissioning showed that the component performance is better than design requirements. This paper describes the construction and commissioning of the permeator and gives the results of the commissioning tests.