This book highlights introduction of thermodynamics; first law, second law, third law of thermodynamics and their applications; concepts of entropy, free energies, thermodynamic equilibrium, thermodynamic activity and fugacity; Maxwell relations; Gibbs-Helmholtz equation; Clausis-Clayperon equation, etc. have been discussed in detail and made easily understandable to the undergraduate students of metallurgy. Thermodynamics involved in formation of different types of solutions (ideal, real and regular solutions) has also been discussed in detail. This book also discusses the applications of various thermodynamic properties in different metallurgical operations. At the end of each and every chapter, different types of typical related problems have also been solved.