The experimental densities rho and speeds of sound u for pure 1-hexyl-3-methylimidazolium tetrafluoroborate ([C(6)mim][BF4]), 1-octyl-3-methylimidazolium tetrafluoroborate ([C(8)mim][BF4]), butylamine (BA), and octylamine (OA) from (293.15 to 323.15) K and binary mixtures of the ionic liquids (ILs) with amines at (298.15, 308.15, and 318.15) K have been reported. The isentropic compressibilities, kappa(S), Rao's molar sound functions, R, intermolecular free lengths, L-f, excess molar volumes, V-m(E), and excess isentropic compressibilities, kappa(E)(S) for binary mixtures were derived. The V-m(E) and kappa(E)(S) of the binary mixtures are negative and decrease with increasing temperature, with the exception of V-m(E) being positive for [C(6)mim][BF4] and [C(8)mim][BF4] + OA in the high IL mole fraction region. The Prigogine-Flory-Patterson (PFP) theory has been applied to interpret the u and V-m(E) data.