A capacitively coupled, atmospheric pressure plasma has been developed that produces a high concentration of reactive species at a gas temperature below 300 °C. The concentration of ground-state oxygen atoms produced by the discharge was measured by NO titration, and found to equal 1.2 vol %, or 1.2±0.4×1017 cm-3, using 6.0 vol % O2 in argon at 150 W/cm3. The ozone concentration determined at the same conditions was 4.3±0.5×1014 cm-3. A model of the gas phase reactions was developed and yielded O atom and O3 concentrations in agreement with experiment. This plasma source etched Kapton® at 5.0 μm/s at 280 °C and an electrode-to-sample spacing of 1.5 cm. This fast etch rate is attributed to the high O atom flux generated by the plasma source.