Four physical properties (solubility, vapor pressure, density, and viscosity) of water + lithium bromide + lithium nitrate + 1,3-propanediol (LiBr/LiNO3 mole ratio = 4, (LiBr + LiNO3)/HO(CH2)(3)OH mass ratio = 3.5) were measured. The system, a possible working fluid for an absorption heat pump, mainly consists of absorbent (LiBr + LiNO3 + HO(CH2)(3)OH) and refrigerant (H2O). Solubilities were measured by the visual polythermal method in the temperature range (285.55 to 346.65) K and in the absorbent concentration range (68.0 to 75.0) mass %. Vapor pressures were measured by the boiling point method in the temperature range (325.35 to 395.15) K and in the absorbent concentration range (46.0 to 69.6) mass %. Densities and viscosities were measured by a set of hydrometers and viscometers, respectively, in the temperature range (283.15 to 343.15) K and in the absorbent concentration range (24.3 to 70.3) mass %. The measured values were correlated.