Abstract: An apparatus and method for producing a high concentration of ozone gas using an electrical corona discharge in the presence of an oxygen containing gas. The generator includes a first and second electrode separated by a dielectric tube, each electrode being adapted to be connected to a high voltage AC power supply. The first electrode preferably has a lattice structure and surrounds the dielectric tube. The second electrode is formed of a mass of helical windings with a series of curved surfaces thereon. The second electrode is positioned within the dielectric tube underlying the first electrode. The curved surfaces of the helical windings create a corona therefrom. In one embodiment of the ozone generator, the mass of helical windings is provided by at least one milled sponge having a plurality of layers of a continuous helical winding extending in a generally spiral direction about a central axis of the milled sponge.