Viscosities and densities of the system (Ag-0.5, Tl-0.5)NO3 + DMSO + H2O were determined in the temperature range 376 less than or equal to T/K less than or equal to 394 K with the mole fraction of the mixed melt, x(s), ranging between 0 and 0.9. This system, formed by the eutectic mixture of AgNO3 and TlNO3 (eutectic point equal to 83 degrees C, AgNO3/TlNO3 mole ratio equal to 1.062) and an equimolar mixture of dimethylsulfoxide with water, is liquid over the specified temperature and composition range. Parameters such as the molar volume, the volume coefficient of thermal expansion, the rheochor and the activation entropy and enthalpy in the Eyring’s equation were determined. An attempt has been made to express these properties by means of single equations, wherein the temperature and composition effects are involved. The behaviour of the system studied here is compared with that of the corresponding (Ag-0.5, Tl-0.5)NO3 + DMSO systems, previously investigated. The results indicate that the partial replacement of DMSO with water decreases the cation-dipole interactions.