Thermodynamic properties of Xe and Cl-2 fluids in subcritical and supercritical regions are studied by using ISM statistical mechanical equation of state (EOS). The second virial coefficients are utilized from those reported by interferometric refractive index measurement over a temperature range almost twice as much as that of available data by PVT measurement. These data and some other data for normal fluids all follow the corresponding states description of second virial coefficients for which the reduced temperature scale T-nfl(*), is defined in terms of the physical properties, in particular the surface tension and liquid density that are available at ambient conditions. Predictions for vapor-saturated liquid densities are accurate within 4%. The prediction for compressed Cl-2 gas is made possible reliably up to 1100 K. For compressed Xe gas the predictions up to 1300 K and 500 bar are within 4%. Predicted excess Helmholtz free energies of the subcritical and compressed supercritical Xe fluid are in reasonable agreement with the molecular dynamic simulation data of (12-6) Lennard-Jonesian. At low temperatures, no agreement with computer simulation data are seen for Cl-2, indicating a pronounced development of multipolar interaction. (c) 2006 Elsevier B.V. All rights reserved.