The high temperature thermal stability, phase transformation characteristics and heat capacity of a Fe-0.28Mn-0.55Si-0.045C (mass%) magnetic iron base alloy have been investigated by dynamic and drop calorimetry techniques. Upon slow heating, the following phase changes are found to take place: αferro + (Fe,Mn)3C → αpara + (Fe,Mn)3C → α + γ → γ → γ + δ → δ → δ + L → L; with distinct enthalpy effects. The α → γ transformation taking place upon slow heating is appreciably influenced by the dissolution kinetics of (Fe,Mn)3C phase. Enthalpy increment values were measured as a function of temperature, up to 1523 K by drop calorimetry. It is found that magnetic effects play a significant role in influencing overall thermodynamic stability. The experimental enthalpy data have been modeled using Debye–Grüneisen and Hillert–Jarl formalisms for accounting respectively the vibrational and magnetic contributions to heat capacity.