In order to investigate the effects of (i) replacing Ni with Co on the catalytic performance of the NiAl2O3 catalyst and (ii) the total metal amount on the catalytic activity of Ni3CoAl for the flue gas reforming of methane (FGRM) reaction at 600 °C, we synthesise a series of active Ni3CoAl2O3 catalysts that are calcined at 850 °C for 5 hours. Strong alloy-support interactions are ensured by maintaining high calcination temperatures. Additionally, we synthesise a Co−Al2O3 catalyst and examine the impact of cobalt promotion using data from a previously synthesised Ni−Al2O3 catalyst. To investigate the impact of total metal loading, we increase the Ni+Co amount from 5 to 25 weight percent while keeping the Ni/Co ratio at 3. The H2-reduction profiles reveal that the temperature where the consumption of H2 was maximum, Tmax temperature, is a function of the total metal loading. The comparison of catalytic activities indicates that in situ reduction of the catalyst at Tmax is better to reduction at elevated temperatures, as it provides a greater number of surface active sites. The CH4 and CO2 conversions and H2 and 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−1 h−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.