A bimetallic and multiply twinned Ag(1-x)Nix (x = 0.2, 0.4, 0.6, 0.8) alloy nanoparticle (MTANP), for the first time has been explored as an efficient heterogeneous catalyst in the industrially important reaction conversion of aromatic amines to the symmetric or asymmetric azobenzenes by the activation of aerobic molecular oxygen. Here, we demonstrated that the as-synthesized and optimized Ag0.6Ni0.4 alloy NPs showed breakthrough in catalytic performance, enabling quantitative aromatic amine conversion and absolute selectivity in azobenzenes (100%) under aerobic green reaction conditions without using the environmentally unfriendly nitrites and any other hazardous materials. A high stability and recyclability of the catalyst are observed and investigated by several instrumental techniques. The key to the effective process is found to be size effect, electronic effect and structural defect, and the presence of surfactant at. the surfaces of the AgNi MTANP catalyst. (C) 2016 Elsevier B.V. All rights reserved.