We report the density (rho) and speed of sound (u) data for 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM] [PF(6)]) + methanol and ([BMIM] [PF(6)]) + acetonitrile binary mixtures over the entire range of their compositions at T = (298.15 to 318.15) K. From these data, excess molar volume and isentropic compressibility deviation values have been calculated and fitted to the fourth-order Redlich-Kister equation. The excess molar volume values (V(E)) for acetonitrile mixtures are more negative than methanol mixtures. Isentropic compressibility deviation values (Delta kappa(s)) in methanol mixtures are more than acetonitrile mixtures. The results have been interpreted in terms of ion-dipole interactions and structural factors of the ionic liquid and these organic solvents.