Layer-by-layer (LBL) assembly is used to produce high-performance nano-structured membrane electrode assemblies for H-2/O-2 fuel cells (see figure) for which porosity, platinum loading, electronic conductivity, and proton conductivity can be finely tuned. Free-standing membranes are made from negatively charged Nafion-wrapped carbon fibers (CFs) and single-walled carbon nanotubes (SWNTs) with Pt nanoparticles deposited by a selective heterogeneous nucleation reaction.