In the framework of the European fusion technology programme, SCK/CEN (Mol, Belgium) has continued the development of an electrolysis cell for highly tritiated water. In the resulting original concept, the liquid inventory is limited to the vertical porous gas separator which is wetted by capillarity. Use is made of thermoelectric heat pumps to cool the cell down to about 8 °C. Intensive testing with light water has been performed successfully during more than 10,000 cumulated hours with mock-up cells, and during more than 6,000 cumulated hours with a prototype cell. These tests have demonstrated the robustness and the long-term reliability of the proposed system. Further experiments are going on with the aim to characterize the working of the capillary cell. In the same time, peripheral equipment such as demisters and cold traps are being tested. These devices are to be incorporated in a dedicated loop for testing with tritiated water at the nominal specific activity (∼ 4.1019 Bq/m3).