PURPOSE: To activate readily a hydrogen-occluded metal within a short period, by treating the hydrogen-occluded metal with a low temperature or high temperature plasma containing H.

CONSTITUTION: Electric waves from an oscillator 1 of about 2,450MHz are introduced through a metal antenna 2 to radiate microwaves through a porcelain tube 3 into a rotary drum type plasma oscillator 4. A gas mixture containing about 50% Ar and about 50% H2 is introduced through a gas inlet-outlet tube 5 at one atmosphere and a constant flow rate of about 500cc/min into the oscillator 4 to produce a low temperature plasma. By rotating the oscillator 4, a hydrogen-occluded metal powder 6 such as a TiF alloy or the like in the oscillator 4 becomes in contact with the plasma, H dissociated from H2 in the hydrogen plasma reduces the oxides on the metal surfaces, and further the H is diffused and occluded into the metal to activate the metal. The activated metal powder is immediately taken out through a takeout valve 7 into a storing vessel 8 the inside atmosphere of which is replaced with H2 so that it wound not become in contact with the atmosphere to be deactivated.