A brief overview is given of the fuel cell families attracting interest today. Problems in the optimization of interfaces in fuel cells, in particular in Polymer Electrolyte Fuel Cells (PEFCs) are discussed next. The influence of the parameters of low precious metal loading, fuel purity, oxygen solubility, and water distribution in the solid polymer electrolyte on the performance of cells are briefly described. Finally, some current problems in the development of Direct Methanol Fuel Cells are presented.