To test Propionibacterium freudenreichii as a novel biocatalyst in a glycerol-oxidizing microbial fuel cell (MFC). Two strains, P. freudenreichii ssp. shermanii and P. freudenreichii ssp. freudenreichii, were screened as anodic biocatalysts and shown to produce power from glycerol in an MFC. Voltage was generated with and without resazurin in the medium, showing that both strains are exoelectrogenic. Polarization data showed that an MFC with P. freudenreichii ssp. shermanii reached a maximum open circuit voltage of 485 mV and a maximum power density of 14.9 mW m(-2). Glycerol consumption was about 50 % lower in MFCs than in fermentations, indicating a metabolic shift in the MFC environment. P. freudenreichii ssp. shermanii and P. freudenreichii ssp. freudenreichii were shown for the first time to act as exoelectrogenic anodic biocatalysts in MFCs.