The heat capacity of diethyl acetamidomalonate (DEAM) has been studied using an adiabatic calorimeter in the temperature range from (78 to 395) K. No thermal anomalies were observed in temperature regions from (78 to 344) K and from (375 to 395) K, where the heat capacity data were fit to two polynomial equations. A solid-liquid phase transition was detected in temperatures from (344 to 375) K The phase transition temperature, enthalpy, entropy and mole fraction purity of this compound were determined to be 368.72 K, 34.3 kJ.mol(-1), 93.0 J.K-1.mol(-1) and 0.9997(mole fraction), respectively, based on the experimental data in the phase transition region. The thermodynamic functions of DEAM relative to the reference temperature of 298.15 K were derived based region. on the fitted heat capacity data in the entire experimental region.