Abstract: A microwave powered ozone producing system comprising a housing defining a microwave cavity having a volume Vo, an inlet and exhaust ports which communicate with the microwave cavity. Disposed within the microwave cavity and uniformly distributed therewithin are a number N of ozone producing lamps, each of which has a diameter D, a length L, and a nominal power p. Communicating with the microwave cavity is a microwave magnetron generator having a microwave power P and producing microwaves having a wavelength .lambda.. Electrically connected to the generator is a power supply. The optimal operating condition for the system to maximize the ultraviolet output and longevity of the lamps and minimize system power consumption is governed by the relationships:Vo.gtoreq.V min 1 wherein V min 1=8 .pi..lambda..sup.3 /3;Vo.gtoreq.V min 2 wherein V min 2=.pi.(D+1).sup.2 N L/4; and ##EQU1## wherein V min is the larger of V min 1 and V min 2, and k is a constant with a value in the range of 0.3.ltoreq.k.ltoreq.3, and .pi.