The main idea of this study is to scrutinize the performance efficiency and enhancement of modelling and simulations of PEM fuel cell. Besides, the research of PEM fuel cell performance can figure out many critical issues for an alternative resource energy. The chapters collected in the book are contributions by invited researchers with a long-standing experience in different research areas. I hope that the material presented here is understandable to a wide audience, not only energy engineers but also scientists from various disciplines. The book contains nine chapters in three sections: (1) "General Information About PEM Fuel Cell", (2) "PEM Fuel Cell Technology" and (3) "Many Different Applications of PEM Fuel Cell". This book presents detailed and up-to-date evaluations in different areas and was written by academics with experience in their field. It is anticipated that this book will make a scientific contribution to PEM fuel cell and other alternative energy resource workers, researchers, academics, PhD students and other scientists both in the present and in the future.