An overview regarding different types of fuel cells is presented. Proton conductive materials are used for low and intermediate temperature fuel cells. Such materials (perfluorinated, partially and non-fluorinated sulfonic acid membranes, and composite membranes) are reviewed. Problems (e.g. proper conductivity attained at high hydration, liquid fuel crossover and high cost) encountered when using these materials as membranes in hydrogen/oxygen and direct methanol fuel cells are emphasized. Concepts, recently reported in the literature and dealing with the development of efficient and less expensive membranes/fuel cells, are also described.