Herein, we report the enzyme-mediated synthesis of bimetallic nanostructure consisting of gold nanoclusters shell- silver nanoparticles core (AuNCs-AgNPs) for catalytic reduction applications. For the synthesis of core AgNPs, thiocholine (TCh), an enzymatic product from the acetylcholinesterase (AChE), and acetylthiocholine (ATCh) interaction was used as a stabilizing agent. The AuNCs-AgNPs was prepared using TCh as a reducing as well as stabilizing agent. The synthesized AuNCs-AgNPs were characterized with help of UV–Vis spectroscopy, dynamic light scattering (DLS) analyses and High-Resolution Transmission Electron Microscopy (HR-TEM). The HR-TEM micrographs confirmed that the formation and arrangement of AuNCs on the core AgNPs, resulting in AuNCs-AgNP bimetallic structures. The catalytic reduction activity of thus prepared AgNPs and AuNCs-AgNPs was investigated against methyl orange (MO) and potassium ferricyanide K3[Fe(CN)6] in the presence of sodium borohydride (NaBH4). The rate constants (k), for MO and K3[Fe(CN)6] catalytic reduction in the presence of AuNCs -AgNPs were measured to be 2.3 × 10− 2 s− 1 and 1.219 × 10− 1 s− 1 respectively. © 2020 Elsevier B.V.