Extraction of egg yolk oil (EYO) from egg yolk pou der (EYP) with supercritical CO2 was performed on a laboratory apparatus. Solubility of EYO in supercritical CO2 was measured. The external diffusion and the equilibrium between solid and fluid phases were experimentally found to be the controlling steps during the extraction process. Based on this mechanism, a mathematical model fur this extraction process was developed. The model parameters, adsorption equilibrium constant (k(p)), EYO concentration in solid controlling the transition in the equilibrium (x(k)) and the overall volumetric mass transfer coefficient (K(1)a(p)). were obtained by simulation. The simulation results indicated that x(k) is 0.56. K(1)a(p) is directly proportional to CO2 flow rate with an exponent of 0.548. and the adsorption heat of EYO is 6-9 kJ mol(-1). The model was verified by concentration profiles of solid. The extraction process of EYO with supercritical CO2 was conducted on a pilot plant and the developed model could predict satisfactorily the process. (C) 2001 Elsevier Science B.V. All rights reserved.