Densities of six binary mixtures containing the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide or 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide mixed with tetrahydrofuran or acetonitrile or dimethyl sulfoxide were determined at atmospheric pressures in the temperature range between 293.15 K and 313.15 K. On the basis of the experimental densities, excess molar volumes were calculated. Comparison of excess molar volumes of six binary systems reveals the slight influence of the IL's cation on these physical properties and the small temperature dependence of V(E) for systems containing dimethyl sulfoxide.