Silver quantum clusters (QCs) stabilized by mercaptosuccinic acid (MSA) have been synthesized at room temperature from Ag nanoparticles through an interfacial etching process. The as-synthesized red emitting QCs were coated on alumina and the supported clusters have been characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive analysis of X-rays (EDAX) and fluorescence spectroscopy. Catalytic activity of Ag QCs supported on alumina have been exploited for the reduction of 4-nitrophenol in presence of sodium borohydride. The reaction followed pseudo-first order kinetics. The catalyst separated from the product remains active and can be recycled several times. Other nitroaromatic compounds have also been tested. Synthesis of the solid phase catalyst, applications and detailed kinetic studies of the reduction of 4-nitrophenol are reported. © 2011 World Scientific Publishing Company.