This study disclosed why and how some decolorized intermediates (e.g., 2-aminophenol) could act as electron-shuttling mediator(s) to enhance the capabilities of reductive decolorization and bioelectricity generation. It also selected several model auxochrome-containing compounds structurally associated to 2AP to explore how chemical structure influenced the feasibility of possible electron shuttles for power producing capabilities in microbial fuel cells (MFCs). The selection criteria of electron-shuttling mediators were suggested for optimal reductive decolorization and bioelectricity generation in MFCs for practical application. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.