The JET Active Gas Handing (AGH) Cryodistillation System (CD) was designed to separate a mixture of hydrogen isotopes into individual isotopic components, discharging low activity protium gas directly to stack, and storing the deuterium and tritium product for re-use. Following successful trace tritium commissioning the system became fully operational for the JET DTE1 experimental campaign which commenced in 1997. This paper describes the operating performance of the CD system during and after this period. This includes an assessment of the total amount of gas processed and the operating conditions which were implemented to achieve optimum process conditions. Note that the original design specification of the system assumed a large proportion of process gas would be protium from the fast pellet injection system. This system was not used during the campaign and consequently the feed gas was mainly a deuterium mix requiring the discharge of large amounts of detritiated deuterium to stack. Hence operating parameters had to be changed to suit these new conditions, which led to a need to keep the tritium inventory in the system to a minimum. Despite this, the overall tritium enrichment in the system with a feed of low activity hydrogen input was up to 35% thus providing an effective pre-enrichment level for introduction to the preparative gas chromatograph (GC) hydrogen isotope separation system used in the AGHS. In this respect even though the operational requirements of CD had changed from the original design specification, the system was successfully adapted to its revised role, providing an important contribution in the tritium reprocessing cycle during the DTE1 campaign.