A new complementary electrochromic device (ECD) is described; it is based on poly(butyl viologen) (PBV) and Prussian blue (PB) confined to the electrode surfaces. PBV is a cathodically colored organic polymer, while PB is an anodically colored inorganic material. The two electrochromic materials were individually characterized in a 0.5 M KCl aqueous solution. On the basis of their properties, a PBV-PB ECD containing a solid-state electrolyte prepared by adding lithium tetrafluoroborate (LiBF(4)) as a salt to succinonitrile (SN) was investigated. This all-solid-state ECD system showed good optical contrast with a coloration efficiency of ca. 163cm(2)/C at 650nm and good stability during 4000 cycles. The transmittance of the ECD at 650nm changed from 73% (bleached) to 8% (darkened), with an applied potential of 1.7V (-1.0 to 0.7V) across the two electrodes. After 4000 cycles, the transmittance attenuation (Delta T) of the device was still at 86% of its original value, i.e. the Delta T value had decreased from 65% to 56%. (C) 2009 Elsevier B.V. All rights reserved.