Nanostructured transition metal nitrides represent a sustainable alternative to conventional materials in a variety of applications, including catalysis, coatings, electrochemical devices, and lithium-ion batteries [1]. Nanoparticles exhibit thermodynamic parameters that can differ significantly from those of bulk materials due to the decrease in dimension [2] and dependence of energetic stability on the surface energy. The investigation of how the thermodynamic parameters of transition metal nitrides differ between bulk and nanoparticles provides the foundation for optimizing these materials for diverse applications. However, compared to other properties (e.g., magnetic, conductive, electronic) that have been measured, thermodynamic investigation is still in its nascent stages. In this study, we employ high temperature oxidative melt solution calorimetry [3] and differential scanning calorimetry to ascertain thermodynamic properties (enthalpy of formation, surface energetics and enthalpy of decomposition) and to identify and discuss stability differences between bulk and nanophases as well as trends among different transition metal (Ti, Fe, Co, and Ni) nitride phases.