Hydroquinone- and naphthoquinone-substituted pyridinium, 2,4'-bipyridinium and 4,4'-bipyridinium salts were prepared. These compounds deprotonate to heterocyclic mesomeric betaines in aqueous solution, which can form conjugated or cross-conjugated tautomers. The redox behavior was studied by cyclovoltammetry. (c) 2006 Elsevier Ltd. All rights reserved.