Calorimetry, as a technique for thermal analysis, has a broad spectrum of applications which are not only restricted to studying the thermal characterization (e.g. melting temperature, denaturation temperature and enthalpy change) of small and large drug molecules, but are also applied to characterization of fuel, metals and oils. Differential Scanning Calorimetry is applied to study the thermal behaviors of drug molecules and excipients by calculating the differential heat flow required to maintain the temperature difference between the sample and reference cells. Microcalorimetry is applied to study the thermal transition and folding of biological macromolecules in dilute solutions and could also be applied in formulation and stabilization of therapeutic proteins. This book consists of research from around the world on the usage of calorimetry on both solid and liquid states of materials and has been grouped under sections: Application of Differential Scanning Calorimetry into Pharmaceuticals, Application of Isothermal Titration Calorimetry for Analysis of Proteins and DNA, and Application of Microcalorimetry to Study Protein Stability and Folding Reversibility.