ESDU 90017 gives equations obtained from a critical evaluation of experimental data in the literature for the variation along the saturation line with temperature, for both the liquid and the vapour, of: density, enthalpy, heat capacity at constant pressure, dynamic viscosity and thermal conductivity. Also given are equations for the variation with temperature along the saturation line of the vapour pressure, latent heat of vaporisation and surface tension, together with equations for the variation with temperature for the ideal gas of specific heat capacity at constant pressure, enthalpy, dynamic viscosity and thermal conductivity. Results on the saturation line evaluated in SI units using the equations are tabulated at 5 K intervals and at 5 degree C intervals from -100 degrees C to the critical point, or as close to it as possible for some properties. Results for the ideal gas evaluated also in SI units using the equations are tabulated at 20 K intervals from the melting point to 1000 K. In the absence of experimental values some of these results involve extrapolation and they are indicated in the tables. Conversion factors to facilitate use of the data in British units are included.