The mechanism of cancer cell death induced by hydrogen discharged from Pd-5at.% Ni hydrogen storage alloy has been investigated. Cancer cell (HeLa : cervical cancer cell) death was observed in the limited region within ~ 3 mm from the sample. The measurement of surviving fraction of cells revealed that almost all the cancer cells in the well of 96-well multi plate, 6.2 mm in diameter were extinct (p < 0.01), while no detectable influence was observed in the normal cells. From the fluorescent imaging experiment, it was indicated that the cell death induced by discharged hydrogen was due to the "Apoptosis" and hydrogen peroxide was detected in both intracellular and extracellular regions. Furthermore, the generation of hydrogen radical and hydroxyl radical was observed in the ESR measurement. From the results obtained, the mechanism of cancer cell death is proposed.

A selective cancer cell death induced by discharged hydrogen from Pd-Ni base hydrogen storage alloy (HSA) powder is demonstrated. From the cell experiment and the measurement of surviving cell rate, it was found that cell death was seen only in cancer cells (HeLa : cervical cancer cell) after 24h-and 48h-immersion of Pd-5at.%Ni alloy powder, while no harmful influence was observed in normal cells (MDCK : renal epithelial cell). The range of cancer cell death was limited just near the HSA powder. It is suggested that the hydrogen radical emitted from the HSA powder induces the formation of hydrogen peroxide and brings a detrimental effect in the cancer cell, while hydrogen peroxide is decomposed by the enzyme, catalase, in normal cells, resulting in the selective death of cancer cells.