TA-beta-CD has been proposed as an effective sustained release carrier for highly water soluble drugs with short biological half-lives. In this work, the possibility of preparing drug -triacetyl-beta-cyclodextrin (TA-beta-CD) complexes in the liquid phase by exploring its solid-liquid-gas equilibrium (S-L-G) under supercritical CO2 atmosphere was evaluated. The S-L-G equilibrium line for the binary system TA-beta-CD + CO2 was determined by a visual method for pressures up to 25.3 MPa. At the studied conditions, a homogeneous and translucent liquid phase emerge at 307 K when exposed to CO2 pressurized at 16 MPa and this temperature further increases with increasing pressure, up to 318K at 25.3 MPa. The S-L-G equilibrium behaviour observed is typical of this kind of asymmetric systems, it is totally CO2 density-dependent and opens the possibility of further processing TA-beta-CD in the liquid phase. In order to investigate the possibility of preparing a drug-TA-beta-CD complex in the liquid phase of TA-beta-CD, a preliminary experiment was performed at 25 MPa and 308 K using flufenamic acid (FA) as the model active principle. (C) 2010 Elsevier B.V. All rights reserved.