ESDU 80017 tabulates values and gives equations for the saturation-line thermophysical properties of a number of fluids suited to capillary heat pipe and thermosyphon use (as described in ESDU 79012 and ESDU 81038). The fluids considered are acetone, ammonia, diphenyl ether/diphenyl (e.g. Dowtherm A), o-dichlorobenzene (e.g. Dowtherm E), methanol, toluene and water which are all suitable fluids operating close to normal temperatures. The properties considered are vapour pressure, density of the saturated liquid and vapour, specific latent heat of vaporisation, specific heat capacity of the saturated liquid, dynamic viscosity of the saturated liquid and vapour, thermal conductivity of the saturated liquid and surface tension. Figures of Merit (parameters based on working fluid properties indicating the relative suitability of the fluids for various operating temperatures) are given for both capillary-driven heat pipes and thermosyphons.