Naturally decaffeinated green tea contains about 2 milligrams of caffeine per cuppa. An average cup of green tea contains approximately 20-30 milligrams of caffeine depending upon the length of infusion. The longer the infusion time, the more caffeine in the cuppa. You may wonder why a decaffeinated tea would have any caffeine in it at all, but most do. For added information, The Republic of Tea uses only a natural CO2 high-pressure extraction process employing carbon dioxide, one of the most expensive yet effective decaffeination processes. Through this method, the caffeine is selectively eliminated from the tea yet the beneficial components of the tea remain. The CO2 method insures flavor, color and quality expectations are met.