This paper describes the characterizations of structural and electrochemical properties of nanoparticle thin films derived by a one-step exchange-cross-linking-precipitation route. While there exists a stepwise layer-by-layer construction method, our motivation stems from seeking an alternative and simpler pathway to prepare such thin films as electrode nanomaterials. The model system consisting of thiolate-encapsulated gold nanocrystals and r,ω-alkanedithiol cross-linkers was studied. The mixing of these two components in solutions allowed sequential exchanging, cross-linking, and eventual precipitation of the dithiol-cross-linked nanocrystals as thin films on almost any substrates. A series of comparative microscopic, spectroscopic, and electrochemical analyses were performed on thin films derived from nanocrystals of 2and 5-nm core sizes. The 5-nm particles were fabricated by size and shape evolution of preformed 2-nm particles. The films were specularly reflecting, electronically continuous, and remarkably comparable with stepwisederived thin films in structural, electronic, and electrochemical properties. The electrochemical data were discussed in terms of thiolate binding and barrier properties of the core-shell structures, which may have potential chemical recognition applications.We report in this paper the characterizations of nanoparticle thin films prepared via a one-step exchange-cross-linkingprecipitation route from gold nanoparticles encapsulated with thiolate monolayers. This class of core-shell nanomaterials is interesting because there are considerable potential technological applications in the areas of microelectronics, optic devices, magnetic materials, catalysis, and chemical recognition. [1][2][3][4][5] Since the first report of the two-phase synthesis protocol, 6 the stable and soluble thiolate-encapsulated nanoparticles have attracted enormous interests. 1 One area is to use such nanoparticles as building blocks toward nanostructured thin films, exploring individual or collective nanoparticle properties. Among several * To whom correspondence should be addressed: (phone)