PURPOSE: To realize an energy generator with good efficiency by supplying deuterium gas to a positive electrode and making a reaction expressed by a particular equation for changing the deuterium gas to deuterium ion.

CONSTITUTION: In the case of using acid electrolyte 3 of D2SO4, deuterium gas D2 is introduced from outside through a valve 7 and the inner pressure of a sealed vessel 6 is set at a specified high pressure. Thus, solving velocity of gas D2 into the solution 3 is expedited and the soluble amount of balance of gas D2 in the solution 3 is increased. The gas D2 penetrates from the gas supply layer 15 in a gas diffusion electrode as a positive electrode 1, diffuses and reaches the boundary between the positive electrode 1 and the solution 3. At this boundary, a reaction occurs as follows. D2→2D++2e-. The produced ion D+ reacts on the electron (e-) supplied from an external power source 9 at a negative electrode 2 to be a deuterium atom D (a), which becomes gas D2 again and at the same time absorbed partly in the negative electrode 2. The electric potential impressed from outside to the positive electrode 1 is lower than 0.1V and the electric potential to cause reaction at the negative electrode 2 is about 0.3V and therefore, the input energy is low enough.