The knowledge of thermodynamic properties and phase transition characteristics of various inorganic and organic materials is essential not only for the fundamental research but also for the industry applications. Thermal analysis is a group of techniques in which one (or more) property of the sample is monitored against time or temperature while the sample, in a specified atmosphere, is subjected to a controlled temperature programme, which can take many different forms. Between the thermal analysis techniques, calorimetry is a universal method for the study of the physical and chemical transformations in a system where heat changes occur. In this work we present different calorimetric methods applied to various materials such as: metallic oxides, phosphates, alloys, amino-acids, proteins etc. Among calorimetric techniques, the drop calorimetry method satisfies many contradictory requirements of different experiments (e.g. low sample mass needed for good transition detection and high sample mass for accurate determination of heat capacity). Enthalpy increments, HT- H298, of Duplex stainless steels (DSS) were obtained employing a drop calorimeter in the isothermal regime using a SETARAM multi-detector high temperature calorimeter (MHTC-96). An advantage of the isothermal drop calorimetry measurements is more accurate values of enthalpy under equilibrium thermodynamic conditions. For comparison, data obtained under varying degrees of nonequilibrium conditions by dynamic or differential scanning calorimetry studies are presented. Data on fundamental thermodynamic quantities contribute in precise quantification of high temperature phase stability and thereby facilitating the materials design and their high temperature processing [1].