The subject of thermal and power engineering is core subject of engineering. The subject has a wide scope and its application is extensive. The Text book focuses the need of first level text book for diploma level students and professional reference for practicing engineer. one of the salient features of this book is written in simple and lucid language with conceptual clarity. The present Text book endeavors to provide relevant theory and principal of thermodynamics and its application of thermodynamic. It is our hope that this book will be a immense value to the technical teachers, students as well as professional n the field. we look forward to receiving invaluable suggestions from the users and experts in the field. This text book could be improved further on the basis of constructive suggestion.