Density (rho) and speed of sound (u) values are measured for the binary mixture of 1-butyl-3-methylimidazolium tetrafluoroborate and aniline over the entire range of mole fraction at temperatures from T = (293.15 to 323.15) K under atmospheric pressure. Using the basic experimental data, molar volume, isentropic compressibility, molar isentropic compressibility, inter molecular free length, excess molar volume, excess isentropic compressibility, excess molar isentropic compressibility and excess intermolecular free length values are calculated. The partial molar volumes and partial molar isentropic compressibilities at infinite dilution have also been calculated. The trends of variation of the parameters have been interpreted in light of the solute-solvent interactions occurring in the system. The excess values are fitted to Redlich-Kister polynomial equation to estimate the binary coefficients and standard deviation between the experimental and calculated values. Further, the molecular interactions in the binary mixture system are analyzed using the experimental FT-IR spectrum recorded at room temperature. (C) 2016 Elsevier Ltd. All rights reserved.