Response surface methodology was used to determine the effects of solvent flow rate (2, 3 and 4 g/min), pressure (30, 37.5 and 45 MPa), temperature (40, 50 and 60 degrees C), and co-solvent concentration (0, 1.5 and 3 wt% ethanol) on oil yield of apricot (Prunus armeniaca L.) kernel oil in supercritical carbon dioxide (SC-CO2). All the parameters had significant effects on oil yield as well as the interactions between solvent flow rate and pressure, and between pressure and temperature. Oil yield increased with increased parameters. The oil yield was represented by a second-degree polynomial equation. The maximum oil yield from the response surface equation was obtained as 0.26 g/g kernel for 15 min extraction of 5 g apricot kernel particles (particle diameter < 0.850 mm) with 4g/min solvent flow rate containing 3 wt% ethanol at 45 MPa and 60 degrees C. The response surface equation predicted the experimental oil yield with a 10% error. The fatty acid compositions of apricot kernel oils extracted with SC-CO2 and hexane were similar. (c) 2004 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved.