en فارماکوگنوزی Pharmacognosy پژوهشي Original Research <strong>Background</strong>: Orange peel essential oils were obtained using supercritical fluid extraction. This method is an important high scaling extraction method used for the extraction of plant and animal extracts.<br> <strong>Objectives</strong>: The aim of this study was the optimization of the extraction of the orange peel essential oil.<br> <strong>Methods</strong>: The experimental parameters of Supercritical Fluid Extraction (SFE) such as temperature, pressure, and extraction time, and modifier volume were optimized using a central composite design after a 24-1 fractional factorial design. Orange peels were collected from ripe orange and were washed, air dried, and milled. Then, a Suprex MPS/225 system in the SFE mode with a maximal operating pressure of 395 bars was used for essential oil extraction. Moreover, GC-MS and GC-FID were used for the identification and determination of oil compounds, respectively.<br> <strong>Results</strong>: Eight compounds have been identified based on their retention indices and mass spectra. According to the results, &alpha;-pinene, &beta;-pinene, myrcene, d-limonene, terpinolene, C8-aldehyde, citronellol, and linalool were identified in orange peel essential oil. The optimum SFE conditions were obtained at a pressure of 347.07 atm, temperature of 55&deg; C, extraction time of 30.16 min, and ethanol volume of 147.05 &micro;L. Moreover, extraction yields based on SFE varied in the range of 0.04% to 1.18% (w/w).&nbsp;<br> <strong>Conclusion</strong>: The Results showed supercritical fluid technology as the best alternative technique for the extraction of pure and high-quality essential oil from orange peel. It is a green method and does not have any environmental impact. Essential oils, Extraction, Supercritical fluid extraction, Volatile compounds 303 312 http://pbr.mazums.ac.ir/browse.php?a_code=A-10-64-2&slc_lang=en&sid=1 Kiana Ghadiri K_Ghadiri@yahoo.com 10031947532846005745 10031947532846005745 No Active Pharmaceutical Research Center (APIRC), Pharmaceutical Science Branch, Islamic Azad University, Tehran, Iran. Farhad Raofie Raofie.F@gmail.com 10031947532846005746 10031947532846005746 No Department of Chemistry, Faculty of Science, Shahid Beheshti University, Tehran, Iran. Mahnaz Qomi Qomi_M55@yahoo.com 10031947532846005747 10031947532846005747 No Active Pharmaceutical Research Center (APIRC), Pharmaceutical Science Branch, Islamic Azad University, Tehran, Iran. Ali Davoodi adavoodi.pharm@gmail.com 10031947532846005748 10031947532846005748 Yes Department of Pharmacognosy and Biotechnology, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran.