The generation of ozone in a stable regime of DC corona discharge at a pin electrode is modeled to provide data that can be utilized for the evaluation of charging and transferring devices of electrophotography with respect to reducing the ozone emission. The results of a theoretical investigation show the following: (1) The ozone generation rates at a 5 liter7slash;min air flow rate for a 50 μm radius pin electrode are 0.085 ppm/μA and 0.010 ppm/μA for negative and positive charging corona, respectively. (2) The ozone generation rate increases with respect to the increase of the pin radius and can be assumed to be linear under normal operation conditions. (3) For positive charging corona, ozone is generated mainly at the surface of the pin electrode, whereas the ozone formation is displaced with a maximum generation rate located at 0.1∼ 0.3 mm from the electrode for negative charging corona. (4) The ozone generation rate for the saw-toothed electrodes is about one-third that of a typical biased charging roller and only 1/140 to that of a corotron.