The relationship between the diversity of mixed-species microbial consortia and their electrogenic potential in the anodes of microbial fuel cells was examined using different diversity measures as predictors. Identical microbial fuel cells were sampled at multiple time-points. Biofilm and suspension communities were analysed by denaturing gradient gel electrophoresis to calculate the number and relative abundance of species. Shannon and Simpson indices and richness were examined for association with power using bivariate and multiple linear regression, with biofilm DNA as an additional variable. In simple bivariate regressions, the correlation of Shannon diversity of the biofilm and power is stronger (r = 0.65, p = 0.001) than between power and richness (r = 0.39, p = 0.076), or between power and the Simpson index (r = 0.5, p = 0.018). Using Shannon diversity and biofilm DNA as predictors of power, a regression model can be constructed (r = 0.73, p < 0.001). Ecological parameters such as the Shannon index are predictive of the electrogenic potential of microbial communities. (C) 2014 Elsevier Ltd. All rights reserved.