Polyaniline (PANI) is considered as one of the most fascinating conductive polymers in fabricating enzyme-based biosensors. Nevertheless, to improve both sensitivity and stability of the PANI-modified biosensor has been and continues to be a technical challenge. In this study, we have electrochemically synthesized the PANI film on a platinum (Pt) electrode and then used this electrode to construct a horseradish peroxidase (HRP)-based biosensor for the detection of hydrogen peroxide (H(2)O(2)). The electrochemical and structural properties of electrodes were characterized with scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier-transform infrared (FTIR) spectrophotometer, and cyclic voltammetry (CV). It was interestingly found that the PANI film synthesized in the presence of bovine serum albumin (BSA) has provided the electrode with enhanced sensitivity and excellent stability. Our results suggested that the embedded BSA might serve as an initial template for aniline polymerization and stabilized the microstructure of the PANI film significantly. The constructed HRP/PANI(BSA)/Pt electrode also exhibited a fine linear correlation with H(2)O(2) concentration. This approach by implanted BSA was useful for improving the sensitivity and stability of PANI-modified biosensor.