Autothermal carbon dioxide reforming of methane was studied over trimetallic NiCoMn/ZrO2 catalyst promoted with different promoters (Ce, La, Ca, K) aiming to improve the performance of the catalyst and increase their resistance to coking. The promoted catalysts prepared by a coprecitation method showed metal sizes less than 10 nm and were studied with a CH4:CO2:O-2 mole ratio of 1:0.8:0.2 at 800 degrees C under atmospheric pressure. The addition of promoters to NiCoMn/ZrO2 catalyst markedly improved CH4 and CO2 conversions as well as selectivities to H-2 and CO relative to the unprompted catalyst. Rare earths Ce and La were more effective promoters than alkaline earth (Ca) and alkali metal (K), showing high and stable CO2 conversions of 95.5% and 89.9%, respectively. The promoted catalysts exhibited higher activity and improved stability with no severe coke deposition and the Ce-promoted NiCoMn/ZrO2 catalyst displayed the highest activity with no apparent activity loss. The roles of the promoters were discussed based on the results of various physicochemical characterization techniques. (C) 2012 Elsevier B.V. All rights reserved.