The mechanism of the LICADO process has been investigated in terms of the surface and interfacial properties of gaseous CO2, liquid CO2, and water in contact with feed coal, clean coal products, and refuse materials. Contact angles of water on the coal surface measured utilizing two different drop-deposition techniques were used to simulate the wetting characteristics of coal in the LICADO process under various mixing conditions. The clean coal particles show a strong hydrophobic behavior which results in their agglomeration and transfer to the liquid CO2phase while the refuse particles, being more hydrophilic, remain in the water phase. The results also showed that an optimum mixing speed is necessary in order to provide enough shearing force to expose the clean coal particles to the CO2droplets. The CO2adsorption on coal surfaces at pressures up to 6.2 MPa and the Dubinin-Polanyi coal surface area measurements indicate that the clean coal samples have higher adsorption isotherms and larger surface areas than those of the corresponding refuse. Consequently, the film pressure and the surface tension of the coal sample were found to increase with increasing ash content. The experimental evidence clearly shows that the LICADO process is a surface property-driven process, governed by the interaction among the interfacial, shearing and body forces present in the coal particle-liquid CO2-water system.