The binary mixtures composed of 1-ethyl-3-(2-methoxyethyl)-imidazolium bis(trifluorome thylsulfonyl)imide [C(2)2O1IM] [NTF2] and alcohols were prepared, and the density and viscosity were measured first across the entire range of mole fraction within a particular temperature range. Based on the experimental values of density, the average molar volume, the excess molar volume, and the partial molar volume were calculated, and the excess molar volume was well fitted by Redlich-Kister equation. In addition, in order to describe the excess activation Gibbs energy of viscous flow simply and directly, the relative volume of mixtures, V-r, is introduced in this paper and then combined with the relative viscosity, eta(r), and a new find about the nondimensional Gibbs energy of activation for viscous flow of the mixture, Delta G(double dagger E)/RT, could be obtained.