This book presents current research in fuel cells which are growing in importance as sources of sustainable energy and are forming part of the changing program of energy resources. Fuel cells provide environmentally friendly, clean and highly efficient energy source for power generation. In order to efficiently utilize the energy from fuel cells, a power conditioning system is required. This book describes the converters' basic operating principles and analyzes performance for low-voltage, high-power fuel cell applications. Full three-dimensional, multi-phase, non-isothermal computational fluid dynamics models of planar and novel tubular-shaped air-breathing proton exchange membrane fuel cell are also presented in detail. Research and review of electrocatalysts such as platinum are presented as well.