Abstract A catalyst system based on Co Mn 2O 3 Ru, with high CO conversion and C 2 C 4 hydrocarbon selectivity, was developed and applied to a new process for converting coke oven gas (COG) into substitute natural gas (SNG). Various carriers were tested for their C 2 C 4 hydrocarbon and CO 2 selectivities and alumina showed the best performance. It was concluded that low Brønsted acidity and larger pore sizes were important for higher hydrocarbon selectivity. By varying the Co-to-Mn atomic ratio and catalyst loading, Co Mn 2O 3 Ru (10:6:2, w/w)/Al 2O 3 was found to be the best catalyst system. This three-component catalyst, used in combination with a CO 2 methanation catalyst, enabled COG to be converted to a high-calorie gas of about 9000 kcal/N m3. The C 2 C 4 hydrocarbon selectivity of the three-component catalyst was slightly increased by treatment with hydrogen or air followed by hydrogen at high temperature, or by the addition of an alkaline earth metal to the catalyst. However, in a fixed-bed reactor the temperature was uncontrollable owing to the exothermic character of this reaction. Therefore, it was concluded that the fixed-bed configuration is unsuitable for industrial application and we introduced a fluidized bed reactor in a pilot-scale study, handling 550 N m 3/h of COG.