A series of solutions composed of air- and water-stable hydrophobic ionic liquids (ILs) [Etpy] [Tf(2)N], [Bupy][Tf(2)N], [PepY] [Tf(2)N], [EtM(4)py] [Tf(2)N], and [BuM(4)py][Tf(2)N] were prepared. The electrical conductivity of the solutions was investigated at T = 298.15 K, respectively. Then the electrical conductivity of solutions of [Bupy] [Tf(2)N] and [HePY][Tf(2)N] in acetonitrile/propylene carbonate were investigated at temperature range from (283.15 to 313.15) K. The correlation of concentration and electrical conductivity was fitted according to the empirical Casteel-Amis (CA) equation. The maximum electrical conductivity was extrapolated by the fitted result. The influence of the successive methylene (-CH(2)-) group and the organic solvent to the electrical conductivity was discussed. The temperature dependence of the electrical conductivity of the solutions, ILs [BupY] [Tf(2)N] and [Hepy][Tf(2)N] in acetonitrile/propylene carbonate, was fitted by the empirical Vogel-Fulcher-Tamman (VFT) equation at a volume ratio of 50%.