There is considerable interest in understanding the catalytical, antibacterial, and photo-thermal properties of Ag nanoparticles. Herein, a simple, scalable and effective method is explored to generate Ag nanoclusters (similar to 3.57 nm) directly on reduced graphene oxide (rGO) (denoted as AgNC/GSH-rGO) using glutathione (GSH) as a green and mild co-reduction agent. Due to the good electrical conductivity of rGO, the extremely small particle size of Ag nanoclusters and the synergistic effect between Ag nanoclusters and rGO, high catalytic activity for reduction of 4-nitrophenol is achieved for AgNC/GSH-rGO at a very low Ag nanoclusters loading of 8.67 wt% on rGO. The conversion could reach 96.69% in 16 min and the apparent rate constant based on rGO is derived to be 0.55 min(-1) when the concentration of AgNC/GSH-rGO is 0.04 mg mL(-1). Moreover, the AgNC/GSH-rGO nanohybrids are also proven to be an efficient antibacterial and photothermal ablation agent for avoiding wound infection and cancer therapy applications. (C) 2018 Published by Elsevier Inc.