TECHNOLOGY FOCUS - ELECTRONICS - Preferred Component: A fuel cell (1) comprises an electrode comprising the electrocatalyst, and an electrolyte membrane. The electrode is a cathode.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The electrocatalyst contains (in weight parts) platinum (10-60), cobalt (1-20) and cerium (0.1-30) with respect to sum of the catalyst support and the metal catalyst (100). Preferred Components: The ternary metal catalyst comprises a platinum-cobalt based metal catalyst (A) and a cerium-based metal catalyst (B). The metal catalyst (A) is platinum-cobalt alloy or platinum-cobalt-cerium alloy. The metal catalyst (B) comprises particles having a core comprising cerium oxide (CeO2) and a shell comprising cerium oxide (Ce2O3). The carbon-based catalyst support is chosen from Ketchen black, carbon black, graphite carbon, carbon nanotube and carbon fiber. The platinum precursor is chosen from chloroplatinous acid, chloroplatinic acid, potassium tetrachloroplatinate, potassium platinum (IV) hexachloride, diamine-platinum compound (Pt(NO2)2(NH3)2) and dihydrogen hexahydroxyplatinate. The cobalt precursor is chosen from cobalt dichloride, cobalt sulfate and cobalt nitrate. The precursor is selected from the group consisting of cerium (III) acetate, cerium (III) bromide, cerium (III) carbonate, cerium (III) chloride, cerium (IV) hydroxide, cerium (III) nitrate, cerium (III) sulfate, and cerium (IV) sulfate. The oxidant used in preparation of the electrocatalyst is hydrogen peroxide. Preferred Arrangement: The metal catalysts (A,B) are located adjacent to each other on the carbon based catalyst support. EXAMPLE - Sodium bisulfite (in g) (5) was added to 1 M solution of hydrated chloroplatinic acid (200) dissolved in water, and stirred to produce a solution of platinum-containing compound (H2Pt(SO3)2Cl6.OH). Hydrogen peroxide (50 ml) was added to the resulting solution to produce platinum oxide (PtO2). Then, cobalt chloride (CoCl2.6H2O) (0.5) and cerium-containing compound ((NH4)2Ce(NO3)6) were added and reacted with hydrogen peroxide remaining in the solution, and cobalt oxide (CoO) and cerium oxide (CeO2) are produced. To the resulting colloid solution, Ketchen black (0.5) was added while bubbling in hydrogen, and stirred for 12 hours. The resulting solid was washed several times with water, and then dried under nitrogen atmosphere at 120 degrees C. Then, the resulting solid product was thermally reduced at 280 degrees C in hydrogen gas to produce platinum-cobalt-cerium ternary electrocatalyst. The obtained electrocatalyst had excellent oxygen reduction reaction efficiency, hydrogen oxidation reaction efficiency and catalytic activity.