Fuel cell technology development is one of the main activities at CNR-TAE Institute. Particular attention was devoted to polymer electrolyte fuel cells (PEFCs), which are the most probable candidates as future energy suppliers for transportation and for portable and domestic applications. The research activity was addressed to new materials and component evolution, system design, and modeling. Because a single cell is not able to supply the desired voltages also for small electronic devices, a PEFC stack of different sizes must be evolved to match the application request. The research activity focused on two different areas: small size stacks for portable applications and medium power stacks for transport and stationary applications. This activity was supported by modeling and computational fluid dynamic studies, and by the evolution of dedicated test station and measurement devices. The first result of PEFC stack research was the development of a stack prototype working at low pressure and based on low Pt loading electrodes evolved at CNR-ITAE. Starting from this experience, a hydrogen fueled air breathing stack of for portable application was realized. The scale up of the cell active area was approached by searching for a method to allow the design of the flow field with specified geometrical characteristics and fluid dynamic properties to maintain the performance reached in small active area cells. A computer-aided design method was evolved, and the design of the active area cell was realized, starting, from a laboratory cell.