The ionic liquid (IL), 2,2-diethyl-1,1,3,3-tetramethylguanidinium ethyl sulfate ([(C-2)(2)(2)(C-1)(2)(C-1)(2)(3)gu]-[C2OSO3]), was synthesized and characterized. The density and viscosity data were determined for the binary mixtures of [(C-2)(2)(2)(C-1)(2)(C-1)(2)(3)gu][C2OSO3] with water, methanol, or ethanol over the whole concentration range at different temperatures T = 293.15-323.15 K and atmospheric pressure p = 0.1 MPa. The excess molar volume, Vm, and viscosity deviation, Or/, for the binary mixtures are calculated and fitted with the Redlich Kister type polynomial equation. The values of VI for [(C-2)(2)(2)(C-1)(2)(C-1)(2)(3)gm][C2OSO3] + water system are observed to be negative, and those for [(C-2)(2)(2)(C-2)(2) (C-1)(2)(3)gu]-[C2OSO3] + methanol/ethanol system change from negative to positive against the mole fraction (x(1)) of the IL, which exhibit the minimum values around x(1) = 0.2 and the maximum values near x(1) = 0.8. The Delta eta values for all of the three binary systems are negative, and the minimum values occur near x(1) = 0.6. The temperature dependence of viscosity for pure [(C-2)(2)(2)(C-1)(2)(C-1)(2)(3)gu] [C2OSO3] and its binary mixtures can be well correlated with the Vogel Fucher Tammann equation. These fundamental physicochemical properties of the binary mixtures make for a better comprehension of the guanidiniumbased ILs and the potential applications.