This article reports an experimental investigation of the possibility of employing the high-temperature air combustion (HiTAC) technique to increase the H2-to-CO ratio in a synthesis gas product. In this study, the exhaust gas from preliminary combustion, which contains oxygen in a low percentage, CO2, and steam, was used in HiTAC combustion and final synthesis gas production. The high-temperature outlet stream (600 degrees 650 degrees C) from the HiTAC furnace, which was free from oxygen, diverted into a catalytic bed to produce the synthesis gas. This newly developed technique was simultaneously involved with the main three methods of synthesis gas production: catalyst reforming, partial oxidation, and water-gas shift reactions. The results show that with an increase in the ratio re-injected to the preliminary methane, the H2-to-CO ratio increased up to 3.3. However, the percentage of H2 and CO in the outlet stream decreased with an increase in this ratio.