The Impurity Processing system of the JET Active Gas Handling System has been upgraded to implement a new catalytic reactor for hydrogen-containing gases, such as hydrocarbons and water, decomposition followed by removal of liberated molecular hydrogen using a palladium permeator. Detritiation of hydrogen-containing species is based on their conversion to molecular hydrogen in the reactions with the carbon-nickel composite. The non-active commissioning of the new modules has been completed.