Forming complexes with cyclodextrins can enhance the dissolution rate, the stability, the solubility and the bioavailability of a drug. In this work, piroxicam/β-cyclodextrin complexes were prepared at solid state by means of supercritical carbon dioxide. The influence of temperature, residence time, water content and a ternary agent, L-lysine, were studied. The complex was characterized by Differential Scanning Calorimetry, Scanning Electronic Microscope and dissolution profile in water. Finally, a complete inclusion was achieved for a piroxicam/β-cyclodextrin/L-lysine mixture by keeping a physical mixture of the three compounds (1:2:1.5 molar ratio) for 2 hours in contact with CO2 at 150°C and 15 MPa.