Excess heat capacities, (C-P(E))(ijk) of {1-methylpyrrolidin-2-one (i) + benzene (j) + o- or m- or p-chlorotoluene (k)} and C-P(E) of their sub-binary {1-methylpyrrolidin-2-one (i) + benzene (j)}; {benzene (i) + m- or p-chlorotoluene (j)} mixtures have been determined using their measured heat capacities data at T = (293.15, 298.15, 303.15) K and 0.1 MPa using micro differential scanning calorimeter. The results are discussed in terms of Graph (which deals with the topology of the constituent molecules) theory. The results suggest that C-P(E) and (C-P(E))(ijk) values commuted by Graph theory compare well with experimental values. (C) 2015 Elsevier Ltd. All rights reserved.