PURPOSE: To constitute a hydrogen reference electrode, which generates a stable electrode potential for a long time, by using a diaphragm shaped electrode comprising Pd or Pd-group primary solid solution alloy.

CONSTITUTION: An electrode container 13 made of hard glass is used. Pure hydrogen gas of 1atm is supplied to a diaphragm shaped electrode main body 11 comprising Pd or Pd-group primary solid solution alloy in the container from a bomb. A hydrogen reference electrode is constituted in an electrode liquid 12 by using 0.1N-HCl. It is confirmed that the main body of the electrode becomes the hydrogen solid solution in the second phase by putting the main body of the electrode in the hydrogen of 1atm. The fact is confirmed by X-ray diffraction. The hydrogen reference electrode, which is constituted in this way, generates a stable electrode potential for a long time.