Reacting tritiated water with hot metal to recover the tritium from tritiated water has been practiced for considerable time. A metal frequently used for this purpose has been uranium. Recent work at the Tritium Systems Test Assembly at Los Alamos National Laboratory has focused on using magnesium for this purpose. This work was done as part of the Annex IV collaboration between the US Department of Energy/TSTA and the Japan Atomic Energy Research Institute/Tritium Processing Laboratory. Magnesium appears to have reactive properties that are as good as uranium and possibly better, and, of course, magnesium is easier to handle and less strictly controlled. Both bench-scale and practical-scale experiments were conducted with magnesium, including tests with tritiated water. Mg bed construction techniques and operating parameters were determined. Testing showed that the Mg packed bed was very effective for recovering hydrogen isotopes from water. However, when used for this purpose, either Mg or U is irreversibly consumed and must be disposed of as tritiated waste. It follows that this processing technique would be inappropriate for a large tritiated water processing operation. However, this technique may find utility for small-scale systems.