Two types of rapidly biodegradable vegetable products (the liquid fraction of clover and the glycerol-containing sidestream from biodiesel production) were selected for anodic oxidation in microbial fuel cells (MFC) equipped with a biocathode. As benchmark references, five abundant amino-acids in plant sap (L-glutamine, L-glutamic acid, L-asparagine, L-aspartic acid and L-alanine) were tested separately. Their performance was in the same order of magnitude of clover sap oxidation (145-225 A m(-3) MFC; 39-95 W m(-3) MFC). Glycerol oxidation resulted in competitive current and power outputs (111 A m(-3)t MFC; 23 W m(-3) MFC).