The heat capacities of Ln(Me2dtc)3(C12H8N2) (Ln = La, Pr, Nd, Sm, Me2dtc = dimethyldithiocarbamate) have been measured by the adiabatic method within the temperature range 78–404 K. The temperature dependencies of the heat capacities, Cp,m[La(Me2dtc)3(C12H8N2)] = 542.097 + 229.576 X − 27.169 X2 + 14.596 X3 − 7.135 X4 (J K−1 mol−1), Cp,m[Pr(Me2dtc)3(C12H8N2)] = 500.252 + 314.114 X − 17.596 X2 − 0.131 X3 + 16.627 X4 (J K−1 mol−1), Cp,m[Nd(Me2dtc)3(C12H8N2)] = 543.586 + 213.876 X − 68.040 X2 + 1.173 X3 + 2.563 X4 (J K−1 mol−1) and Cp,m[Sm(Me2dtc)3(C12H8N2)] = 528.650 + 216.408 X − 16.492 X2 + 12.076 X3 + 4.912 X4 (J K−1 mol−1), were derived by the least-squares method from the experimental data. The heat capacities of Ce(Me2dtc)3(C12H8N2) and Pm(Me2dtc)3(C12H8N2) at 298.15 K were evaluated to be 617.99 and 610.09 J K−1 mol−1, respectively. Furthermore, the thermodynamic functions (entropy, enthalpy and Gibbs free energy) have been calculated using the obtained experimental heat capacity data.