The excess heat capacities, C-P(E) and (C-P(E))(ijk) (calculated from the measured molar heat capacities, C-p data) of binary 1-ethyl-3-methylimidazolium tetrafluoroborate (i) + pyrrolidin-2-one or 1-methylpyrrolidin-2- one or pyridine (j); pyrrolidin-2-one (i) + pyridine (j) and ternary 1-ethyl-3-methylimidazolium tetrafluoroborate (i) + pyrrolidin-2-one or 1-methylpyrrolidin-2-one (j) + pyridine (k) mixtures have been measured as a function of composition at T = (293.15, 298.15, 303.15 and 308.15) K and 0.1 MPa using micro differential scanning calorimeter. The (C-P(E))(ijk) values for the present ternary mixtures are positive over entire range of composition. The C-P(E) and (C-P(E))(ijk) data have been fitted to Redlich-Kister equation to compute binary and ternary adjustable parameters along with their standard deviations. The topology of the constituent molecules (Graph theory) has been utilized to obtain the expressions that describe well the C-P(E) and (C-P(E))(ijk) data of the present mixtures. It has been observed that Graph theory describes well the C-P(E) and (C-P(E))(ijk) data of the binary as well as ternary mixtures. (C) 2014 Elsevier Ltd. All rights reserved.