The ternary solid complex has been synthesized with sodium diethyldithiocarbamate (NaEt2dtc?3H2O), 1,10-phenanthroline (o-phen?H2O) and hydrated neodymium chloride in absolute ethanol. The title complex was identified as the general formula of Nd(Et2dtc)3(phen) by chemical and elemental analyses. IR spectrum of the complex showed that the Nd3+ coordinated with six sulfur atoms of three NaEt2dtc and two nitrogen atoms of o-phen. It was assumed that the coordination number of Nd3+ is eight.The enthalpy change of liquid-phase reaction of formation, ?rHm (l), was determined as (-12.274±0.050) kJ?mol-1 at 298.15 K by a microcalorimeter, the Θ enthalpy change of the solid-phase reaction of formation, ?rHm (s), was calculated as (149.069±0.314) kJ?mol-1 Θ on the basis of a thermochemical cycle. The thermodynamics of reaction of formation was studied by changing the temperature of liquid-phase reaction. The constant-volume combustion energy of the complex, ?cU , was deter- mined as (-18674.22±8.33) kJ?mol-1 by a precise rotating-bomb calorimeter at 298.15 K. Its standard enthalpy of combustion, ?cHm , and standard enthalpy of formation, ?fHm , were calculated as (-18693.43±8.33) kJ?mol-1 Θ Θ and (-47.03±9.17) kJ?mol-1, respectively. The ternary solid complex has been synthesized with sodium diethyldithiocarbamate (NaEt2dtc®3H2O), 1,10-phenanthroline (o-phen®H2O) and hydrated neodymium chloride in absolute ethanol. The title complex was identified as the general formula of Nd (Et2dtc) 3 (phen) by chemical and elemental analyzes. IR spectrum of the complex showed that the Nd3 + coordinated with six sulfur atoms of three NaEt2dtc and two nitrogen atoms of o-phen. It was assumed that the coordination number of Nd3 + is eight. Enthalpy change of liquid-phase reaction of formation,? rHm (l), was determined as (-12.274 ± 0.050) kJ? mol- 1 at 298.15 K by a microcalorimeter, the? enthalpy change of the solid-phase reaction of formation,? The thermodynamics of reaction of formation was studied by changing the temperature of liquid-pha (149.069 ± 0.314) kJ-mol-1 Θ on the basis of a thermochemical cycle se reaction. The constant-volume combustion energy of the complex,? cU, was deter- mined as (-18674.22 ± 8.33) kJ? mol-1 by a precise rotating-bomb calorimeter at 298.15 K. Its standard enthalpy of combustion,? cHm, and standard enthalpy of formation,? fHm, were calculated as (-18693.43 ± 8.33) kJ? mol-1ΘΘ and (-47.03 ± 9.17) kJ? mol-1, respectively.