Liquid liquid equilibrium data and phase diagram corresponding to new (salt + salt) aqueous biphasic system composed of tetra-n-butylammonium bromide and trisodium citrate were determined by varying temperature and atmospheric pressure. The effects of temperature and salt induced on the binodals and tie-lines of the investigated ATPS were also studied. It was found that an increase in temperature caused the expansion of the two-phase region and increased the slope and the length of the tie line. In order to obtain further evidence about the salting-out effect produced by the addition of trisodium citrate, Na(3)Cit to an aqueous solution of water-miscible tetra-n-butylammonium bromide, volumetric and compressibility behavior have been measured at temperatures (298.15 K-318.15 K). The densities and speeds of sound data have been utilized to calculate apparent molar volumes, V-phi, the apparent molar isentropic compressibility, k(phi), the values of the apparent molar quantity at infinite dilution, (V phi S)-S-circle, k(phi)(circle) and partial molar characteristics include the volume and compressibility of transfer at infinite dilution, Delta Y-t(phi)circle, TBAB from pure water to the aqueous salt solution. (C) 2016 Elsevier B.V. All rights reserved.