In the Chemical Engineering Department at the University of Valladolid (Spain), a pilot plant for soil remediation with supercritical CO2 extraction and subsequent adsorption on activated carbon has been developed. Soil polluted with hydrocarbons from a petrochemical plant has been treated in order to reduce the pollution level below legal limits. Operational parameters such as extraction temperature, solid particle size, and solvent ratio were optimized. Experiments were conducted at a 30-60 degreesC extraction temperature, combined with a temperature of 50 degreesC for the adsorption onto activated carbon. The solvent flow rate was varied between 5 and 15 kg/h, and the effect of particle size in the process was studied for particles with dp < 0.425 mm. Several experiments have shown that a gradient in temperature is necessary between the extraction step and the adsorption step and that extraction temperature should be lower than adsorption temperature. Results show that temperature increases improved both initial rates of extraction and total recoveries, maintaining in every case the gradient mentioned above. The solubility of the contaminant in the SCF does not limit SFE, and diffusion into the CO2 phase was found to be the limiting step in the extraction rate. Results show an optimal extraction temperature of 40 C, particle size of 0.425 mm, and solvent ratio of 15.8 kg CO2[(kg soil) h]. A comparison of this soil with the same soil contaminated with diesel oil in the laboratory has been made. The effect of particle size is particularly strong for the soil recently spiked in the laboratory; in the studied range of particle sizes, the bigger the particles, the better the extraction. That can be explained by the fact that, for aged soil, pollutants are more strongly adsorbed on the soil and the effect of particle size is not as important as the bond forces.