In this study, we synthesize a series of active Ni3Co–Al2O3catalysts, calcined at 850 °C for 5 h, to examine the effects of (i) substituting Ni with Co on the catalytic performance of the Ni–Al2O3catalyst and (ii) the total metal amount on the catalytic activity of Ni3Co–Al for the flue gas reforming of methane (FGRM) reaction at 600 °C. We maintain high calcination temperatures to ensure strong alloy–support interactions. We also synthesize a Co–Al2O3catalyst and use the data of a previously synthesized Ni–Al2O3catalyst to analyze the effect of cobalt promotion. In the Ni3Co–Al catalysts, we maintain the Ni/Co ratio to be 3 and increase the Ni+Co amount from 5 to 25 wt % to examine the effect of total metal loading. The H2-reduction profiles reveal that the temperature where the consumption of H2was maximum, Tmaxtemperature, is a function of the total metal loading. Comparison of the catalytic activities appears to suggest that in situ reduction of the catalyst at Tmaxwas better than the reduction at higher temperatures, since a larger number of surface active sites are available. The CH4and CO2conversions and H2and CO yields increase when nickel is substituted with cobalt due to Ni–Co nanoalloy formation. However, the dispersion of the nanoalloy varies with the metal loading, and the optimum dispersion is when Ni+Co = 10 wt %. This 10Ni3Co–Al catalyst exhibits optimum CH4(89%) and CO2(30%) conversions and H2(79%) and CO (46%) yields for the FGRM reaction at 600 °C for a GHSV of 120,000 mL g–1h–1. The conversions, yields, and particle size of the alloy of this 10Ni3Co–Al catalyst do not change significantly, and an insignificant amount of carbon is formed during 24 h of operation. Thus, after using a promoter, it is necessary to optimize the loading of the active phase to obtain the best catalyst for FGRM.