The structure of the Cl- hydration shell in high-temperature (77 and 197 degrees C) and supercritical (375 degrees C) water at moderate densities (roughly twice the critical density of 0.356 g/cm(3)) as well as in water at an ambient temperature, is investigated by means of neutron diffraction with isotope substitution on Cl- in aqueous 3 and 9 m solutions of LiCl in D2O. These relatively high densities (compared to the critical density) are used here to maintain the salt solubility at a sufficiently high value that a measurable signal is obtained in the isotope difference. The data are subjected to an empirical potential structure refinement which enables individual site-site radial distribution functions to be estimated. The same structure refinement is also used to estimate the spherical harmonic coefficients of the Cl- water orientational pair correlation function, and these are used in turn to reconstruct the local environment around Cl- in solution. A marked disordering of the Cl- hydration shell is observed as the critical point is approached. The orientational correlation functions of the water-molecule dipole vectors around Cl- in ambient water show a strong peak at a distance of about 3.2 Angstrom, and centered at an angle of about 126 degrees +/- 630 degrees,with respect to the Cl-O (D2O) axis,confirming an almost linear CL ... D-O hydrogen bond but with a significant spread of orientations about this value. At the higher-temperatures the peak remains at about the same position, but becomes progressively weaker in amplitude and with a larger spread of angles, suggesting a gradual decrease in orientational correlation of the water molecules around Cl-. At the supercritical temperature, the peak is even weaker, and there is evidence for a broader hydration shell developing at a distance of r approximate to 3.9 Angstrom in which the water molecules are apparently randomly oriented: they apparently become more loosely packed than at lower temperatures, without being dispelled from the ion hydration shell.