Interest in environmental pollution is increasing all over the world, and technology development to solve it is actively carried out. In areas where heat is used, especially, combustion is causing countless pollutants in the air environment. Combustion catalyst is a technology that reduces NOx and CO by lowering combustion temperature and enabling complete combustion. Traditional combustion catalysts are expensive and complex in the synthesis process using precious metal catalyst. In this study, hexaaluminate, a high-temperature combustion catalyst, was manufactured using urea, and the properties were investigated according to the synthesis time. The combustion performance and characteristics were evaluated using this catalyst. As the temperature increased, the changing methane conversion rate was shown in two patterns. The conversion rates for 1 hour, 9 hours, and 12 hours were similar, while the conversion rates for 3 hours and 6 hours showed similar patterns. Methane combustion performance increased rapidly as the synthesis time increased from 6 hours to 9 hours, whereas the temperature at T50 was approximately 745 ℃. The performance of the synthesized combustion catalyst for 9 hours was optimum as the NOx emission of this combustion catalyst was not present and the maximum emission of CO was 72 ppm.