Amperometric biosensors based on the physical immobilization of phytase (PhyA) into polypyrrole (PPy) films were prepared in aqueous medium. The PPy/PhyA films were characterized by cyclic voltammetry, and surface and structural characterization techniques, SEM and FTIR. Both voltammetric and amperometric transduction methods were used in order to detect phytic acid in acetate buffer at pH 5.5 at room temperature. The biosensors exhibited a detection limit of 0.15 mmol L-1 and a linear range of phytic acid content from 0.5 to 2.0 mmol L-1, which are adequate values for typical analyses of phytic acids in most seeds, grains, and vegetables ; FAPESP ; CAPES ; CNPq