The purpose of this study was to investigate obtaining of caffeine from tea plant wastes by supercritical carbon dioxide extraction. Experiments were carried out with tea stalk and fiber wastes of Turkish tea plants that has no economical value. Stalk and fiber wastes were supplied from tea factories. These wastes were ground, sieved and dried at 105 degrees C temperature in an oven. Parameters affecting caffeine leaching from tea wastes were determined to be, extraction time, extraction temperature, carbon dioxide flow rate, process pressure and particle size. The maximum yield of caffeine from tea stalk wastes and fiber wastes were 14.9 mg/g tea stalk and 19.2 mg/g tea fiber, respectively. The yield increase had been recorded as 61.9% and 65.5%, respectively, in comparison with the chloroform extraction of tea stalk and fiber wastes. (C) 2009 Elsevier B.V. All rights reserved.