Platinum nanoparticles as a catalyst for proton-exchange-membrane fuel cells (PEMFCs) were grown on nitric acid-treated multiwalled carbon nanotubes by atomic layer deposition (ALD) at 250 degrees C. Formation of uniform and well-distributed Pt nanoparticles was achieved. The size and number of Pt nanoparticles could be controlled by the ALD cycle number. The PEMFC test shows that for the membrane electrode assembly made of both anode- and cathode-deposited Pt (0.019 and 0.044 mg cm(-2), respectively) after 100 cycles of ALD has 11 times higher specific power density than that made of commercial E-Tek electrodes containing 0.5 mg cm(-2) of Pt. (C) 2012 Elsevier Inc. All rights reserved.