Two air and water stable hydrophobic ionic liquids N-alkyl-4-methylpyridinium bis(trifluoromethylsulfonyl)imide ([C(n)4mpy][NTf2], n = 2, 4) were synthesized and characterized. The density, electrical conductivity, and dynamic viscosity were measured and estimated in the range of T = (278.15 to 363.15) K. The melting temperature, glass transition temperature, and decomposition temperature of the two ILs were determined according to the differential scanning calorimetry (DSC) and thermogravimetric analyzer (TG). The molecular volume, standard molar entropy, and lattice energy were estimated in terms of empirical equations on the basis of the density values. The electric:I conductivity and dynamic viscosity values dependence on temperature were fitted by the Vogel-Fulcher-Tamman equation. The molar conductivity was calculated by the density and electrical conductivity.