In the present investigations, the excess molar volumes, , excess isentropic compressibilities, , and excess heat capacities, , for ternary 1-butyl-2,3-dimethylimidazolium tetrafluoroborate (i) + 1-butyl-3-methylimidazolium tetrafluoroborate (j) + 1-ethyl-3-methylimidazolium tetrafluoroborate (k) mixture at (293.15, 298.15, 303.15 and 308.15) K and excess molar enthalpies, , of the same mixture at 298.15 K have been determined over entire composition range of x (i) and x (j) . Satisfactorily corrections for the excess properties , , and have been obtained by fitting with the Redlich-Kister equation, and ternary adjustable parameters along with standard errors have also been estimated. The , , and data have been further analyzed in terms of Graph Theory that deals with the topology of the molecules. It has also been observed that Graph Theory describes well , , and values of the ternary mixture comprised of ionic liquids.