In principle, a fuel cell operates like a battery. Unlike a battery, a fuel cell does not run down or require recharging. It will produce energy in the form of electricity and heat as long as fuel is supplied. A fuel cell consists of two electrodes sandwiched around an electrolyte. Oxygen passes over one electrode and hydrogen over the other, generating electricity, water and heat. Fuel cells which run at low temperatures require efficient catalysts. The majority of catalysts are made primarily of platinum (Pt). Due to the rarity of this metal, scientists are experimenting with doping Pt with such metals as palladium (Pd) or ruthenium (Ru) and complexes of cobalt and nitrogen to help reduce amount of catalyst and the cost of producing a purely platinum catalyst. Decreasing the amount of precious metal in the electrode catalysts is a major challenge in the development of fuel cells. Such a reduction in the amount of metal catalyst in most cases can be achieved by increasing the active area of platinum that is actually utilized on an electrode surface. One way to achieve this is by using high surface area carbon supports, which generally enable higher utilization of the metal catalyst. The electrophoretic deposition of SWCNT on a carbon fiber electrode (Toray paper) provides a simple and versatile technique to design a membrane electrode assembly (MEA) for the fuel cell. SWCNT serve as an excellent support to anchor Pt catalyst and carry out electrochemical oxidation and reduction reactions effectively similar to the existing commercial carbon black support. The effectiveness of SWCNT supported Pt and Pt-Ru catalyst has been evaluated successfully in hydrogen and direct methanol fuel cells, DMFCs For example, Pt-Ru catalysts dispersed on SWCNTs exhibit lower onset potential for methanol oxidation. The onset potential for methanol oxidation correlates well with the maximum power density of a DMFC. Based on the evaluation of the electrochemical and fuel cell performances one can conclude that no single property of the carbon nanostructures dictates the performance of electro catalysts in the MEA. Along with electrochemical active surface area of the MEA, the metallic character of carbon nanotubes is important in attaining higher power density in a DMFC. Nearly 30% enhancement in the power density is seen when these carbon nanotubes are used in the MEA instead of carbon black. Accelerated durability tests indicate that SWCNTs enhance the stability of the electro catalyst during long-term use. The lower energy of CO adsorption observed with a Pt/SWCNT electrode also demonstrates the CO tolerance of this electrocatalyst. Both supported and unsupported colloidal nanomaterial precursors have also been used to prepare electrocatalysts for fuel cells. Fine particulate colloidal platinum sols are ideal precursors for the manufacture of fuel cell electrodes. Nanostructured metal colloids are also very promising precursors for manufacturing multi-metallic fuel cell catalysts that are truly nanosize (less than 3 nm) and have high metal loadings (30 wt% of metal). The nanocolloid catalysts are typically based on bi- or tri-metallic particles and offer improved efficiency and tolerance towards contaminants. They are under active investigation as catalysts in low-temperature proton-exchange membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs).