Research Octane Number (RON) is a benchmark for the quality of fuel oil based on the octane value, which indicates the level of knocking or knocking produced by the fuel when combustion occurs in the vehicle engine. RON value is influenced by the composition of branched and aromatic carbon naphtha hydrocarbons. Ultra Low Sulfur Diesel (ULSD) is a type of fuel that has a sulfur content that can be overcome by the hydrotreating process. One of the hydrotreating processes is to remove sulfur, nitrogen, oxygen, and other metals, which is known as the hydrodesulfurization (HDS) process. The purpose of this study was to determine the temperature variation of the high-olefin racing fuel feed to produce a low sulfur content of 10 mg/L and a stable RON value of the feed with a minimum RON 95 value. Therefore, the catalyst used in this experiment is a catalyst containing the active metal cobalt (Co), namely a CoMo/ɣ-Al2O3 catalyst with a concentration of 0.5 (% w/w), which has been characterized using a surface area analyzer (SAA), X-ray fluorescence (XRF), and X-ray diffraction (XRD). The catalyst activity tested in the microreactor effi PID with temperature variations of 250 °C, 260 °C, and 270 °C to reduce the amount of sulfur in the racing fuel feed. The products produced from the reactor tested for sulfur content using a total sulfur analyzer and then tested using GC-DHA (Gas Chromatography Detailed Hydrocarbon Analysis) to determine and analyze the RON values and the content of n-paraffin, isoparaffin, olefins, naphthene, and aromatics (PIONA) contained in the product. Synthesized CoMo/ɣ-Al2O3 catalyst has a wide area of 175.49 m2/g, a pore diameter of 98.95 Å, and a pore volume of 0.52 cc/g. The active metal content of the CoMo/ɣ-Al2O3 catalyst produced based on XRF analysis is 0.55 % w/w for CoO content and 7.82 % w/w for MoO3 content. The CoMo/ɣ-Al2O3 catalyst products can reduce the sulfur content produced to 31.33, 26.09, and 20.45 mg/L at various temperatures of 250 °C to 270 °C. These results were still below the Euro 5 standard, namely 10 mg/L at a concentration of 0.5 % w/w, and also did not obtain optimal temperature variations for the hydrodesulfurization process, resulting in a decreased RON value from the feed used.