TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Process: The evaporated precursors are maintained at temperatures near the boiling points. The reactor in the step of heating the reactor is heated at 300 degrees C or above. The platinum precursor and the organic precursor are supplied to the reactor in the step of heating, in a state in which the ratio of the flow rate of the platinum precursor to the flow rate of the organic precursor of 0.2-10. Preferred Components: The platinum precursor is (trimethyl)methylcyclopentadienyl platinum, platinum(II) acetylactonate, tetrakis(trifluorophosphine) platinum(0), tetrakis(triphenylphosphine) platinum(0), platinum(II)hexafluoroacetylacetonate, trimethyl(methylcyclopentadienyl) platinum(IV) or (1,5-cyclooctadiene)dimethyl platinum(II). The carrier gas is oxygen, hydrogen, argon, helium or nitrogen gas. The support is carbon paper.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The organic precursor for formation of the carbon framework is methanol, ethanol, acetone, benzene, toluene, xylene, methane or acetylene. EXAMPLE - Methylcyclopentadienyl platinum was used as a platinum precursor and acetone was used as a carbon precursor. Quartz filter was placed in 1 inch quartz tube to capture a metal-carbon composite and the inside of the quartz tube was maintained at 120 degrees C for 2 hours in a nitrogen atmosphere to remove water and impurities. The inside of the each of two evaporators placed in ovens was maintained in a nitrogen atmosphere, and inlet and outlet corks were all closed, and in this state, nitrogen was passed through a bypass line for 30 minutes or more without passage through the evaporators to impurities from a reactor. Then the reactor was heated to 400 degrees C at a rate of 10 degrees C/minute to make composite synthesis conditions, and at a time point when the temperature of the reactor reached the desired reaction temperature, the temperature of oven 1 provided with the evaporator containing the platinum precursor was elevated to 60 degrees C and the temperature of oven 2 containing acetone was elevated to 55 degrees C. At a time point when the temperatures of each precursor and the reactor reached the desired temperatures, the cork of each evaporator was opened so that carrier gas including each evaporated precursor reached the reactor. Nitrogen was used as the carrier gas. 40 sccm of nitrogen was passed through oven 1 containing the platinum precursor and 20 sccm of nitrogen was passed through oven 2 containing acetone and 40 sccm of nitrogen was additionally passed through the reactor by a separate line. At a time point when the cork was opened, the synthesis reaction started and a reaction time of 2 hours from that time point was maintained to obtain a core-shell platinum-carbon composite.