Infrared absorption measurements of diluted perdeuterated water in supercritical carbon dioxide are reported. The frequency shift of the anti-symmetric stretching mode (v(3)) is analysed using an analytical molecular model to get insights into the water-CO2 interaction. Attractive forces, namely, dispersive and dipole-quadrupole interactions, are found dominant in the stabilisation energy of the water-CO2 pair. Differences between observed and calculated frequency shifts reveal local density enhancements (LDE). The observation of LDE at temperature greater than the critical one (T/T-c greater than or equal to 1.3) allows to conclude that water acts as an.attractive solute in the hyper-compressible regime of the solvent. (C) 2004 Elsevier B.V. All rights reserved.