A device for generating ozone from oxygen-containing gas by silent electric discharge. At least two high-voltage electrodes and at least one ground electrode are nested. A discharge gap is defined between each high-voltage electrode and adjacent ground electrode. A dielectric is arranged in each discharge gap. In one embodiment, at least two discharge gaps are traversed by the gas, and a different voltage is applied to each gap according to the individual gap width. In another embodiment, filler material is arranged in an interstice between the high-voltage electrode and the corresponding dielectric, and the same amount of power is applied to each discharge gap.