[en] When the system metal-dielectric-metal is irradiated with X or γ-rays, an electromotive force is induced. The induced electromotive force strength is about 1 Volt and is proportional to the ionizing radiation intensity. The potential difference induced during ionization causes in this metal-dielectric-metal system a current flow range 10^-11 - 10^-14 A, without an external voltage source. An electromotive force is induced in the ionization chamber when the electrodes are of different materials or of the same material. This fact suggests, that the ionization induced potential difference is caused by surface photo-voltaic effect as well as by volume effect. (author)