It is well known that Au-Ag bimetallic nanoparticles have better performance in catalytic processes compared to their counterpart pure clusters. The improvement in their catalytic properties has been attributed to a kind of synergy between the gold and silver atoms that has not been fully understood. Unlike pure clusters, there are very few studies on the catalytic behavior of the Au-Ag binary nanoparticles. From the theoretical point of view, in the subnanometer regimen, the bimetallic Au-Ag clusters present a challenging problem, since by combining the different gold and silver relativistic effects, a variety of skeletal geometric structures and homotopic distributions are obtained. In particular, pure gold has favorable planar structure even up to 16 atoms, while silver begins to favor 3D arrangements from 5-7 atoms. This dissimilar behavior produces a diverse population of 2D and 3D coexisting binary clusters, whose properties strongly depend of the Au/Ag mixing ratio. In this work we use the relativistic approach ZORA-DFT to model the AunAgm (with 4 ≤ (n + m) ≤ 12) binary nanoclusters in selected proportions (1:1, 3:1, 5:1) in the gas-phase and we study their reactivity from the descriptors based in the condensed Fukui indexes obtained from an NBO electronic population analysis.