Electroactive viologen-functionalized silica core-shell nano-composites have been prepared and characterized using thermogravimetry, field emission transmission electron microscopy, and infrared, UV-vis absorption, and X-ray photoelectron spectroscopy. The viologen monolayer functionalized nanosilica core (nano-SiO(2)VBen) was obtained via a substitution reaction of propylamine - modified silica nanoparticles (nano-SiO2NH2) with N, N'-di(bromomethylbenzyl)-4,4'-bipyridium dibromide (VBenBr(2)). The nano-SiO(2)VBen core was positively charged and could thus act as a support for the construction of the shell layer of viologen multilayers through, alternatively, the electrostatic adsorption of poly(sodiump- styrenesulfonate) (PSS) and VBenBr(2). Dynamic light scattering and morphological studies revealed that the dynamic sizes of the nanoparticles increased in the following order: nano-SiO2NH2, nano-SiO(2)VBen, and nano-SiO(2)VBen@(PSS/VBen)n. This was due to the assembly of organic multilayers around the nanoparticles and formation of aggregates. Cyclic voltammograms of nano-SiO(2)VBen-and nanoSiO(2)VBen@(PSS/VBen) n-modified electrodes showed two couples of redox waves in the potential range from 0 to - 1.2V (vs Hg/Hg2Cl2), corresponding to the redox processes of viologens in the nanocomposites. Compared to their precursor of VBenBr(2), the nano-SiO(2)Ben and nano-SiO(2)VBen@(PSS/VBen) n composites could be more strongly adsorbed on the electrode surface without co-adsorption of the polymeric supporter (Nafion), which can be attributed to a stronger molecular interaction between the present nano-composites and electrode surfaces. Finally, the redox-induced electrochromic properties of VBenBr(2) and nano-composites were investigated in the solutions or polymer gel electrolytes, and the results suggest that both viologen organic electrolyte and nano-composites could act as potential candidates for the development of redox-based electrochromic indicators and displays. (C) 2017 Elsevier Ltd. All rights reserved.