The Prussian blue nanoparticles (PBNPs) were prepared by a self-assembly process, on a glassy carbon (GC) electrode modified with a poly(o-phenylenediamine) (PoPD) film. The stepwise fabrication process of PBNPs-modified PoPD/GCE was characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy. The prepared PBNPs showed an average size of 70 nm and a homogeneous distribution on the surface of modified electrodes. The PBNPs/PoPD/GCE showed adequate mechanical, electrochemical stability and good sensitivity in comparison with other PB based H2O2 sensors. The present modified electrode exhibited a linear response for H2O2 reduction over the concentration range of 1–58.22 mmol L1 with a detection limit of ca. 0.8 mmol L1 (S/N = 3), and sensitivity of 3187.89 mA (mol L1)1 cm2 using the amperometric method. This sensor was employed for the H2O2 determination in real sample and also exhibited good interference resistance and selectivity.