The paper reports on the construction and operating characteristics of a planar dielectric barrier discharge (DBD) plasma generator. The generator was powered from a commercial frequency inverter at 400 Hz through a high voltage transformer. It could be operated up to a specific energy density (power per gas flow) of 20 Wh/m(3). The corresponding power density was about 0.5 W per cubic centimeter of discharge volume. Special emphasis was given to a simple and reliable construction, which was easy to assemble and is based on a new, nonexpensive barrier material with excellent electrical, mechanical, and thermal properties. The modular reactor design allows simple plasma power scale-up. The reactor works with undried ambient air without additional cooling. In the range up to 10 Wh/m(3) the ozone generation from ambient air was directly proportional to the energy density at a rate of 60 g O-3 per kWh or 30 ppm/Wh/m(3). Thus the generator can serve as an effective source for chemically active radicals in plasma gas cleaning applications.