The properties of pure xenon have been extensively studied and techniques have been developed for its use in, for example, the preparation of inert solid matrices, the filling of ionization chambers and as an anaesthetic in medical research. However, the use of liquid Xe as a solvent has been limited to a few small-molecule solutes such as hydrogen halides and formaldehyde, in a temperature range below and near the Xe melting point1-7. We now present experimental evidence in the form of UV, visible, IR and NMR spectra which show that liquid Xe can be used as a fluid solvent for several biological and organic molecules at temperatures from near room temperature to -100 C. Solid Xe solutions also provide a means of studying spectra of large or heat-sensitive molecules which cannot be investigated by traditional matrix isolation methods. 1981 Nature Publishing Group.