This book contains six chapters that detail the properties and applications of nanocomposite membranes. Chapter One provides an overview of the nanocomposite membrane, preparation methods, and gas transport mechanisms. Then, properties and applications of nanocomposite membranes in gas separation are reviewed. Chapter Two focuses on the overview of fuel cell technology, especially proton-exchange membrane fuel cells. Chapter Three introduces nanocomposite polymer electrolyte membranes and their advantages for Li batteries application. Chapter Four covers the topic of nanocomposite membranes and their wide range of applications. In Chapter Five, the development of nanocomposite membranes as the latest developed generation of reverse osmosis and nanofiltration membranes for desalination and water purification applications is reviewed. Lastly, Chapter Six discusses how nanocomposites have been involved in the development of novel concepts with the great potential for plant disease management.