The book publishes the latest research by prominent American scientists on fuel cells and on certain issues of the theory of their work. Each chapter is written by leading experts in the field. The book is of great interest, since fuel cells - devices in which the energy of chemical oxidation reactions of different types of fuel is directly converted into electrical energy - have received great development in recent years. The book is designed for graduate students, scientific and engineering workers engaged in research and the use of chemical sources of current, as well as dealing with the problem of direct conversion of chemical energy into electrical energy.