TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The OMC composite catalyst comprises metal particles (0.05-0.45, preferably 0.005-0.1 parts by weight based on 1 part by weight of the OMC). The catalyst comprises the sulfur-containing carbon precursor (30-90 parts by weight based on 100 parts by weight of the nitrogen-containing carbon precursor) and the metal precursor (20-120 parts by weight based on 100 parts by weight of the nitrogen-containing carbon precursor). Preferred Components: The metal of the metal particles is at least one selected from ruthenium, palladium, iridium, iron, cobalt, molybdenum, and nickel. The OMC has mesopores have an average diameter of 6-10 nm. An average particle diameter of the metal particles is 1-50 nm. The component includes both nitrogen and sulfur, and a mixed atomic ratio of nitrogen to sulfur is 1:3-9:1. The OMC composite catalyst has X-ray diffraction pattern as given in the specification. The nitrogen-containing carbon precursor is at least one selected from quinoxaline, propylene diamine, 4,4-dipyridyl and phenanthroline. The sulfur-containing carbon precursor is para-toluene sulfonic acid. The metal precursor is at least one selected from ruthenium chloride, molybdenum chloride, iron chloride, and cobalt chloride. EXAMPLE - A first ruthenium precursor solution was prepared as follows. As a nitrogen-containing carbon precursor, quinoxaline (purity 99%) (0.512 g) used as an OMS template was used. Ruthenium chloride (0.150 g) was used as a ruthenium precursor, where the amount of ruthenium was 0.1 parts by weight based on 1 part by weight of the synthesized OMC. The nitrogen-containing carbon precursor and the ruthenium precursor were mixed to prepare a mixture. The first ruthenium precursor solution was prepared by mixing and completely dissolving distilled water (0.96 g) and para-toluene sulfonic acid (0.337 g) constituting a sulfur-containing carbon precursor and a carbonization catalyst in the above mixture. A second ruthenium precursor solution was prepared in the same manner as the first ruthenium precursor solution, except that 70% of the amount of the first ruthenium precursor solution was used. A first impregnation process was performed by putting OMS, which was used as a template and the first ruthenium precursor solution prepared above in a Teflon (RTM: fluoro polymer) bottle and shaking the Teflon bottle. The mixture inside the Teflon bottle was dried and reacted in an oven at 160 degrees C for 6 hours in order to form an oligomer. The color of the mixture darkened as time passed. The resultant was cooled down at room temperature, and then, a second impregnation process was performed by using the second ruthenium precursor solution. Then, the impregnated resultant was reacted in the oven at 160 degrees C for 6 hours. The composite power obtained as above was carbonized at 900 degrees C under a nitrogen gas atmosphere. Here, the temperature was increased up to 900 degrees C for 5 hours, and maintained constant at 900 degrees C for 2 hours. The resultant was processed by using a hydrogenfluoride (HF) solution so as to remove the OMS. Accordingly, an OMC composite catalyst (Ru-N-S-OMC) was obtained.