NOVELTY - Graphite oxide is milled and calcined to obtain expanded graphite oxide. Expanded graphite oxide is placed in a beaker, and ethylene glycol and deionized water are added, stirred, and ultrasonically processed. Ethylene glycol solution of chloroplatinic acid is added and stirred to adjust pH to 7-9. Stirring is continued and the reaction mixture is placed in a microwave reactor for 1-3 minutes. After reaction completion, the reaction mixture is cooled, filtered, washed, and dried to obtain a platinum/graphene catalyst having a platinum content of 20 wt.%.    USE - Preparation of platinum/graphene catalyst for use in fuel cells.    ADVANTAGE - The method enables preparation of platinum/graphene catalyst by using expanded graphite oxide as precursor, without addition of additional dispersant. Hence, reduction in catalytic activity by presence of residual dispersant is prevented, and better oxygen reduction performance is achieved.    DETAILED DESCRIPTION - A 250-ml three-necked flask is placed in an ice-water bath, and 80-120 ml concentrated sulfuric acid, 1-3 g flaky graphite, and 0.5-1.5 g sodium nitrate are added and mechanically stirred. 10-15 g Potassium permanganate is slowly added in 1-4 hours and stirred in the ice bath for 2-10 hours. The reaction mixture is then placed in an oil bath, heated to 35-40 degrees C, and maintained for 5-20 hours. 80-160 ml Deionized water is slowly added to the mixed solution and heated at 85-95 degrees C for 15-30 minutes. The flask is removed from the oil bath and cooled to room temperature. 10-30 ml Hydrogen peroxide solution is added and the solution turned from brown to bright yellow. The solution is washed hydrochloric acid and then with deionized water until neutral, and vacuum-dried to obtain graphite oxide. Graphite oxide is milled into a powder and calcined in a muffle furnace at 800-1000 degrees C to obtain expanded graphite oxide. 3-6 mg Expanded graphite oxide is placed in a beaker, and 30-60 ml ethylene glycol and 0-50% deionized water are added, stirred, and ultrasonically processed for 20-40 minutes. 0.1-0.3 ml 0.0386 mol/L Ethylene glycol solution of chloroplatinic acid is added and stirred to adjust pH to 7-9. Stirring is continued for 10-20 minutes, and the reaction mixture is placed in a microwave reactor for 1-3 minutes. After reaction completion, the reaction mixture is cooled to room temperature, filtered, washed, and dried to obtain a platinum/graphene catalyst having a platinum content of 20 wt.%.