In this research, extraction of an essential oil from Cleome coluteoides Boiss aerial parts was investigated using supercritical carbon dioxide (SC-CO2) technique for the first time. Design of experiments and process optimization was carried out with response surface methodology (RSM) based on the central composite design (CCD). Influence of operating parameters including pressure (P = 100-220 bar), temperature (T=308-328 K), particle size (d(p) = 0.3-0.9 mm) and dynamic extraction time (t=30-150 min) on final response was evaluated. The experimental values were adequately fitted to a quadratic polynomial equation. Analysis of variance (ANOVA) results indicated that all factors were significantly affected the extraction yield of essential oil from C. coluteoides. Using a grey wolf optimization (GWO) algorithm, the optimal operating conditions were determined to be P = 220 bar, T = 308 K, d(p) = 0.58 mm and t = 135 min, under which conditions, the maximum yield of 0.6589 was obtained. Chemical compositions extracted by hydro-distillation (HD) and SC-CO2 methods were identified by gas chromatography/mass spectrometry (GC/MS) and determined by GC/FID. Comparing the two methods, the obtained results showed higher total extraction yield with SC-CO2 technique. (C) 2016 Elsevier B.V. All rights reserved.