The study of hexanethiol-passivated gold nanoparticles is reported. Depending on the age of the solution two kind of structures are obtained, "foam-like'' in fresh solution and "cluster-like'' few weeks after the solution preparation. Both kind of structures have been studied regarding to their structural and electrical properties. The cluster-like structures have shown lower electrical resistivity compared to foam-like ones. Some other factors like sonication, have shown to have no effect on the formation of one or another kind of structure. (C) 2009 Elsevier B.V. All rights reserved.