The effect of Pd-WO3-SiO2 nanocomposite on the electrochemical behavior of Prussian blue nanoparticles (PBNPs) is investigated. The Pd-WO3-SiO2 is made from tungstic acid sol followed by sonication with palladium linked 3-Glycidoxypropyltrimethoxysilane sol. The homogenized sol is then allowed to form gel under ambient conditions and calcinated at 600 degrees C. PBNPs sol is made as described earlier [Electrochimica Acta. 87 (2013) 1-81 and mixed with Pd-WO3-SiO2 followed by sonication and drying at 65 C. The resulting Pd-WO3-SiO2-PB shows average size to the order of 85 nm as characterized by transmission electron microscopy. The nanocomposite shows excellent peroxidase mimetic and electrocatalytic behavior for H2O2 analysis and experimental finding justified the following conclusions; (1) WO3 and Pd-WO3-SiO2 gradually improve the catalytic efficiency of PBNPs, (2) WO3, Pd-WO3-SiO2 and Pd-WO3-SiO2-PB shows peroxidase mimetic behavior having catalytic efficiency in the order of Pd-WO3-SiO2-PB > Pd-WO3-SiO2 >WO3, (3) Pd-WO3-SiO2-PB nanocomposite exhibits excellent electrocatalytic property for H2O2 sensing with catalytic rate constant to the order of 7.5 x 104 M-1 s(-1) HRP-modified Pd-WO3-SiO2-PB shows 7 fold enhanced analytical sensitivity as compared to that of Pd-WO3-SiO2-PB system. (C) 2014 Elsevier Ltd. All rights reserved.