Rosehip seed oil has been extracted using supercritical CO2 at various operating conditions to optimize extraction process. The effect of extraction conditions on the fatty acids composition in the oil was also observed. The extraction conditions were as follows: pressures (P) of 150, 300 and 450 bar, temperatures (1) of 40, 60 and 80 degrees C, and CO2 flow rate (F) of 2, 3 and 4 mL/min. A full 3(3) factorial design coupled with statistical and graphical analysis of the results, by using analysis of variance (ANOVA) was applied to optimize variables in the process of rosehip seed oil extraction with SC-CO2. The experimental result showed that the seed oil extracted mainly contained linoleic acid (C18:2) as the most abundant followed by linolenic (C18:3), palmitic (C16:0) and stearic acid (C18:0); and the extraction conditions influenced the fatty acids composition. The analysis of experimental design for process optimization results demonstrates that temperature and pressure were to be the influential variables on the extraction yield of seed oil. Furthermore, the apparent solubility of oil in SC-CO2 was also determined from the experimental data and correlated using empirical equations for further model developing. (C) 2007 Elsevier B.V. All rights reserved.