A newly designed electrolytic device to enrich tritium in environmental water is proposed. This device is composed of a solid polymer electrolytic film (SPE film) and porous, dimensionally stable electrodes (DSE) . In our design a platinum mesh was inserted between the SPE film and the anode DSE so that the device can be easily disassembled and the used SPE film can be replaced with a new one after each use. A thin gold plate with a number of minute holes in it is used as current collector in both electrodes allowing the electrolytic gas to be released progressively. An electrolytic current of 6A was passed through the device to obtain a volume reduction factor of five by keeping a temperature of water bath at 2°C or lower. After that, our device achieved a tritium recovery factor of 0.836 ± 0.021 (n=4) . Such a value is greater than the value obtained using a commercially available apparatus operated under the same experimental conditions. It is thought that this greater efficiency depends on the difference between electrolytic temperature produced in our device and the temperature in the commercially available one.