Analysis of process data from initial detritiation tests in a pilot-scale Combined Electrolysis and Catalytic Exchange (CECE) Facility1 indicated that very high detritiation factors (DFs), at least 10 000, could be achieved in the facility. Performance requirements for process equipment were evaluated and some minor refinements were made to selected components. In particular, the recombination efficiency of tritium in the electrolytic oxygen stream was improved and the tritiated-water feed point was moved to a location lower in the catalyst column. With these modifications, the facility was able to remove more than 99.998% of the tritium (i.e., achieve a DF greater than 50 000) from a heavy water feed stream containing 330 GBq/kg, with 7.8 TBq/kg in the electrolysis cell. The processing rate at these conditions was about 2.2 Mg/a, compared with a rate of 5 Mg/a for a DF of 180.