Effect of peracetylated beta-cyclodextrin on the solubility of diphenyl(4-phenylphenyl)phosphine in supercritical carbon dioxide medium has been investigated. As shown by gravimetric measurements, the presence of cyclodextrin (CD) (1 equivalent) allows to increase the solubility of phosphine (P) in supercritical carbon dioxide (scCO(2)) (40 degrees C, 35.2 MPa, nominal system density 0.89 g/mL). This solubility enhancement was attributed to host-guest interactions in scCO(2) as the P was recovered in the form of an inclusion complex. Furthermore, a diffuse reflectance spectroscopy study on the samples recovered after the experiments and on various CD/P solid mixtures obtained by co-grinding indicates that the (4-phenylphenyl) group of the P was included in the host cavity of the peracetylated beta-CD. (c) 2005 Elsevier B.V. All rights reserved.