NOVELTY - Functionalizing a carbon material, involves contacting a carbon material with a carboxylic acid, thereby forming a mixture; and heating the mixture for a suitable period of time at a temperature below the thermal decomposition temperature of the carbon material, thereby forming a functionalized carbon material.    USE - For functionalizing carbon material e.g. carbon nanotube and carbon nanowire with functional group such as -COOH, -CHO, -CO-, -OSO3H and OH, for immobilizing matter on a carbon material for forming particles of metal (such as noble metal e.g. rhodium, rhenium, ruthenium, palladium, platinum, silver and/or gold), metal oxide, metalloid and metalloid oxide on carbon material useful in catalysis for oxidation and/or reduction in a fuel cell (claimed).    ADVANTAGE - The method is simple and efficient for functionalizing carbon materials and for forming highly dispersed metal nano-particles on carbon materials. The method provides citric acid modified multi-walled carbon nanotubes having more functional groups on the surface of carbon nanotubes when compared to acid refluxed multi-walled carbon nanotubes. The method provides platinum (Pt) nanoparticles supported on citric acid modified multi-walled carbon nanotubes having higher activity than Pt supported on acid refluxed multi-walled carbon nanotubes. A high density of functional groups can facilitate the dispersion of Pt catalysts and can enhance the removal of carbon monoxide (CO) intermediates during the electrochemical processes.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for immobilizing matter on a carbon material, involving contacting a carbon material with a carboxylic acid, thereby forming a mixture; heating the mixture for a suitable period of time at a temperature below the thermal decomposition temperature of the carbon material, thereby forming a functionalized carbon material; and contacting the functionalized carbon material with a compound capable of forming a covalent bond and/or an ionic bond with the functional groups on the functionalized carbon material.