In this report, a novel method for the synthesis of gold nanoparticles on an amorphoussilica support is described wherein silanol groups on the surface of the fumed silicaspontaneously reduce aqueous chloroaurate ions. This results in the formation of goldnanoparticles that are bound fairly strongly to the fumed silica surface. Alkylamine moleculespresent in solution were observed to reduce the size of the gold nanoparticles thus formedby self-assembling on the nanoparticles and preventing further growth. The gold nanoparticlesize is dependent on the concentration of alkylamine molecules in solution. The goldnanoparticle-fumed silica composite material was found to be catalytically active in thehydrogenation of cyclohexene.