A general mathematical model for supercritical CO2 adsorption on activated carbon has been developed. Adsorption curves obtained with a laboratory plant (adsorber of 10 ml) have been fitted by with this model and the results have been extrapolated to adjust the breakthrough curves obtained with a pilot plant (adsorber of 11). Moreover a wide range of operating conditions has been covered, extraction pressures from 14.7 to 20.0 MPa, temperatures between 30 and 50degreesC and CO2 flow-rates ranging between 0.12 and 0.36 kg/h. The proposed model takes into account equilibrium (adsorption isotherm), diffusion in the solid (effective diffusion coefficient, D-e), mass-transfer from the bulk of the fluid phase to the surface of the solid (mass-transfer coefficient related to the supercritical solvent, k(f)), axial dispersion (effective dispersion coefficient, D-az) and a first order reversible adsorption/desorption reaction at the solid surface site (adsorption and desorption kinetic constants, k(a) and k(d)). In order to get a suitable adjust, the experimental adsorption curves have been represented by this model by fitting the kinetic coefficients (k(a), D-e and D-az) to the experimental curves, obtained from the laboratory installation. The parameters k(f) and k(d) are calculated, k(f) by well-known correlation and k(d) by the determination of adsorption isotherm. A fair good fitting of all the available experimental laboratory results has been obtained using D-e values ranging between 2.4 and 4.8 x 10(-9) m(2)/s, D-az values of 1.2-3.2 m(2)/s and k(a) values of 1.4-1.5 m(3)/kg s. With these optimised parameters it is possible to model the adsorption curves obtained with the pilot plant with reasonable accuracy (standard deviation, 7-11%). (C) 2004 Elsevier B.V. All rights reserved.