Food wastes were used as feedstock for the direct production of electricity in a microbial fuel cell (MFC). MFC operations with volatile fatty acids (VFA) produced 533 mV with a maximum power density of 240 mW/m(2). Short-chain VFAs, such as acetate, were degraded more rapidly and thus supported higher power generation than longer chain ones. In general, the co-existence of other, different VFAs slowed the removal of each VFA, which indicated that anodic microbes were competing for different substrates. 16S rRNA gene analysis using PCR-DGGE indicated that the MFC operation with VFAs had enriched unique microbial species.