Essential oil of Biebersteinia multifida DC cultivated in Iran was obtained by hydrodistillation (HD) and pressurized hot water extraction (PHWE) methods. The oil was analyzed by capillary gas chromatography using flame ionization and mass spectrometric detections. The effects of different parameters such as temperature, pressure, static extraction time, dynamic extraction time, and flow rate on the PHWE and radical scavenging activity of B. multifida oil were optimized using circumscribed central composite. Fifty two compounds were identified in the HD oil. The major components of B. multifida were (E)Nerolidol (31.45%), Hexadecanoic acid (11.84%), Phytol (17.1%), and 6,10,14-trimethyl-2-pentadecanone (15.4%). However, by using pressurized hot water extraction in optimum conditions, obtained only four components contain more than 86% of the essential oil. The optimum extraction yield and DPPH EC50 via PHWE method were 5.1% (w/w) and 28.40, respectively. (C) 2014 Elsevier B.V. All rights reserved.