The triarylimidazoles (TAIs) constitute a promising class of organic electron transfer redox mediators that have been used to achieve indirect electrochemical C-H bonds activation and functionalization. Herein we report the diffusion and electron transfer rates for the oxidation of 4-methoxybenzyl alcohol using TAI and compare its electrochemical behavior with that of tris(4-bromophenyl)amine (TBPA). The results contribute to our understanding of the electron transfer process of electrocatalytic oxidation using TAIs, and offer useful guidelines for their further development and use. (C) 2014 Elsevier Ltd. All rights reserved.