This article gives an overview of the challenging issues addressing different technological fields in generating power using fuel cell. Continuous depletion of crude oil supply and the gradual increase in oil prices have emphasized the need for a suitable alternative to the century-old oil-based economy. Among the different technological alternatives, fuel cell (FC) power generation becomes a more promising solution for both automotive industry and stationary power plants. Among the five existing FC technologies, each type can be configured into a system focusing on the market segments that match its characteristics most favorably. Because of their quick startup potential, low-temperature is being considered for portable, residential power and transportation applications. Higher- temperature are often considered for stationary power generation. Nevertheless, due to their solid electrolyte, SOFCs are also considered for transportation applications by some car manufacturers and car suppliers. Diagnosis methods based on evolutionary parameter models, black-box models, or grey-box models must be developed to improve reliability and availability of FC systems. The equivalent circuit approach addresses electrical engineering concerns and suits the system integration issues.