A novel nonenzymatic hydrogen peroxide (H2O2) sensor was fabricated, based on composite Pd-Co oxide films modified n-silicon electrode. The modified electrode was consisted of platinum coated n-silicon as substrate prepared by vacuum evaporating a platinum coating and composite Pd-Co oxide films deposited by electrochemical technique. The morphology of the modified electrode was characterized via scanning electron microscope (SEM). The analytical performances of the modified electrode for determination of H2O2 were investigated by cyclic voltammetry (CV) and chronoamperometry. A new two electrodes photo-electrochemical cell has been used as sensor for H2O2 determination by photocurrent measurements at zero voltage. The sensor showed good photocurrent responses by adding different concentrations of H2O2 with a good stability. The linear ranges for the detection of H2O2 are 2 to 48 μM with a detection limit of 0.57 μM in pH=7.0 phosphate buffer solution (PBS). In addition, the sensor also exhibited superior stability, anti-interference and portability. These features demonstrated that the new photo-electrochemical sensor was suitable for detection of H2O2 on site outdoors.