The formation of the spherical self-assembly of gold nanoparticles (AuNPs) of 200 ± 20 nm size at the water–chloroform interface is achieved by employing the cyclotetrasiloxane [RSCH2CH2SiMeO]4 (R = CH2CH2OH) as the stabilizing ligand. The interfacially stabilized AuNPs act as a versatile catalyst for selective hydrolytic oxidation of only one of the Si–H bonds in secondary organosilanes, RR1SiH2 (R