A series of electrochromic metal complex nanosheets comprising 1,3,5-tris(4-(2,2':6',2″-terpyridyl)phenyl)benzene or 1,3,5-tris((2,2':6',2″-terpyridyl)ethynyl)benzene and Fe(2+) or Co(2+) was synthesized. The preparation of multilayered nanosheets was achieved by liquid/liquid interfacial synthesis using an organic ligand solution and an aqueous metal-ion solution. The resultant nanosheet had a flat, smooth morphology and was several hundreds of nanometers thick. Upon its deposition on an indium tin oxide (ITO) electrode, the nanosheet underwent a reversible and robust redox reaction (Fe(3+)/Fe(2+) or Co(2+)/Co(+)) accompanied by a distinctive color change. Electrochromism was achieved in a solidified device composed of the nanosheet, a pair of ITO electrodes, and a polymer-supported electrolyte. The combination of Fe(2+) and Co(2+) nanosheets in one device-deposited on each ITO electrode-demonstrated dual-electrochromic behavior.