The solid polymer electrolysis apparatus for natural tritium enrichment had a flow pass to exchange water in the reservoirs of anode and cathode sides. In this study, electrolysis was investigated for tritium water only in the anode side, in which the flow pass was closed. The accompanying water obtained in the cathode side showed a tritium enrichment factor of 1.3, and no tritium enrichment was observed in the anode side. Multi step of this batch electrolysis should be useful to achieve further enrichment of tritium.
