Among various technologies using hydrogen-energy, fuel cells have been considered as the most energy efficient technology. A conventional combustion-based power plant typically generates electricity at efficiencies of 33 to 35 percent, while fuel cell plants can generate electricity at efficiencies of up to 60 percent. When fuel cells are used to generate electricity and heat (co-generation), they can reach efficiencies of up to 85 percent. Moreover, fuel cells generate virtually zero pollution including greenhouse gases such as CO₂. Therefore, the fuel cells are believed as a most promising alternative power producing technology, which can solve global problems facing 21st century such as exhaustion of fossil fuels and environmental pollution at the same time. In this review, recent trends in fuel cell R&D are summarized focusing on PEMFC and DMFC which are closest to the practical use and can be used for batteries, electrical power sources for automobiles and immobile structures such as buildings.