In order to syngas formation, combined steam and carbon dioxide reforming of methane (CSCRM) used in the presence of Ni-Pd/Al2O3 catalysts, which were synthesized by the solgel method. Al2O3 supported Ni-Pd catalyst exhibited the appropriate surface area of 176.2 m(2)/g and high dispersion of NiO phase with an average crystallite size of 11 nm, which was detected on catalyst surface utilizing transmission electron microscopy (TEM). The influence of three independent operating parameters including reaction temperature in the range of 500-1000 degrees C; (CO2 +H2O)/CH4 ratio, in the range of 1-3 and CO2/H2O ratio; in the range of 1-3, were investigated on the responses (i.e., CH4 conversion, H-2 yield, CO yield, amount of coke formation on the catalyst surface and H-2/CO ratio) in CSCRM by using response surface methodology-central composite design (RSM-CCD) method. The obtained results from ANOVA and the proposed quadratic models could fine forecast the responses. It was seen that the total methane conversion and CO yield was almost accessible at temperatures higher than 850 degrees C. Moreover, the CO2/H2O ratio exhibited no significant effect on the CH4 conversion, H-2 yield and CO yield of Ni-Pd/Al2O3 catalysts in CSCRM reaction. However, the high CO2/H2O ratio in inlet feed led to the syngas formation with a low H-2/CO ratio. The results revealed that lower CO2/H2O ratio and higher temperature as well as higher (CO2 + H2O)/CH4 ratio help to decrease the coke formation. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.