Au/G4OH nanocomposites were synthesized in aqueous solutions under different conditions and used as precursors for the preparation of SiO2-supported Au nanoparticles. Elemental analysis, UV-Vis, and STEM measurements were used to determine the nature and the extent of the Au-dendrimer interactions and to illustrate how the solution pH affects the Au-dendrimer complexation, as well as the final size of the gold particles formed. G4OH PAMAM dendrimers were found to reduce Au3+ ions and act as stabilizers for Au nanoparticles thus formed, yielding stable gold/dendrimer colloidal solutions. The solution pH and the Au/G4OH ratio were found to be two critical factors that control the size of gold particles. At pH 7, Aus/G4OH nanocomposites with sizes of Au particles below 2 nm can be formed and used as precursors for the preparation of solid materials. Such nanocomposites can be deposited intact on the surface of SiO2 and yield highly dispersed and nearly uniform Au nanoparticles with dimensions in the order of 1.3 nm. (C) 2014 Elsevier B.V. All rights reserved.