The temperature profiles in a monolith reactor were measured in CO₂ reforming of CH₄ with in-situ combustion of methane and ethane in order to find out in what sequence the reactions are occurring. The reaction gas flowed both upward and downward. A hot spot was observed at low furnace temperatures, and it tended to disappear as the furnace temperature increased. This is due to natural extinguishment of the flame caused by the endothermic reforming reactions occurring. The hot spot disappeared at a lower temperature with the up-flow when compared with the down-flow. When the hot spot appears, H₂O and CO₂ are produced by complete oxidation and accordingly the steam reforming and the CO₂ reforming occur competitively in the rear part of the monolith. If the hot spot does not appear, it is considered that the partial oxidation of methane occurs predominantly over the complete oxidation, resulting in more efficient CO₂ removal.