The influence of duty cycle on ozone generation and discharge characteristics was investigated experimentally using volume dielectric barrier discharge in both synthetic air and pure oxygen at atmospheric pressure. The discharge was driven by an amplitude-modulated AC high voltage-power supply producing T-ON (a single AC cycle) and T-OFF periods with a widely variable duty cycle. The experimental results show that the energy delivered to the discharge during each AC cycle remains roughly constant and is independent of feed gas, duty cycle and T-OFF. Both average discharge power and ozone concentration show an initial linear increase with duty cycle, and deviate gradually from linearity owing to an increase in gas temperature at higher duty cycles. Nevertheless, ozone yield remains nearly constant (45.7 +/- 3.5 g/kWh in synthetic air and 94.7 +/- 3.1 g/kWh in pure oxygen) over a wide range of applied duty cycles (0.02-1). This property can be conveniently employed to develop a unique ozone generator with a widely adjustable ozone concentration and simultaneously a constant ozone yield. Additionally, the discharges in synthetic air and pure oxygen have similar electrical characteristics; however, there are observable differences in apparent luminosity, which is weak and white-toned for synthetic air discharge, and bright and blue-toned for pure oxygen discharge.