The standard molar enthalpy of formation of crystalline diethyldithiocarbamate complexes of Cd and Hg(II) has been derived by solution calorimetry at 298.15 K, giving -227.5 +/- 5.0 and - 141.4 +/- 5.0 kJ mol(-1), respectively. The corresponding standard molar enthalpies of sublimation, 102.0 +/- 3.5 and 129.2 +/- 4.2 kJ mol(-1), were estimated by means of differential scanning calorimetry. From the standard molar enthalpies of formation of the gaseous chelates (-125.5 +/- 6.1 and - 12.2 +/- 6.5 kJ mol(-1)), the homolytic (167.3 +/- 3.6 and 74.6 +/- 3.6 kJ mol(-1)) and heterolytic (695.0 +/- 3.6 and 733.4 +/- 3.6 kJ mol(-1)) mean metal-sulphur bond-dissociation enthalpies were calculated. The results correlate with the characteristics of the metals and cations in the gas phase.