Two different flexible osmium redox polymers; poly(1-vinylimidazole)(12)-[Os-(4,4'-dimethyl-2,2'-di'pyridyl)(2)Cl-2](2+/+) (osmium redox polymer I) and poly(vinylpyridine)-[Os-(N,N'-methylated-2,2'-biimidazole)(3)](2+/3+) (osmium redox polymer II) were investigated for their ability to efficiently "wire" Pseudomonas putida ATCC 126633 and Pseudomonas fluorescens (P putida DSM 6521), which are well-known phenol degrading organisms, when entrapped onto cysteamine modified gold electrodes. The two Os-polymers differ in redox potential and the length of the side chains, where the OS2+/3+-functionalities are located. The bacterial cells were adapted to grow in the presence of phenol as the sole source of organic carbon. The performance of the redox polymers as mediators was investigated for making microbial sensors. The analytical characteristics of the microbial sensors were evaluated for determination of catechol, phenol and glucose as substrates in both batch analysis and flow analysis mode. (c) 2006 Elsevier B.V. All rights reserved.