A non-enzymatic hydrogen peroxide (H2O2) sensor based on a vertically aligned gold nanowire array electrode modified with palladium nanoparticles (PdNP/AuNAE) has been fabricated. PdNP have been deposited onto the AuNAE surface by a hydrothermal reduction method using a borohydride technique. Scanning electron microscope inspection (SEM) has revealed granular Pd particles deposited on the surface of the nanowires. X-ray diffraction (XRD) peak analysis has determined an average crystallite size of 3 to 5 nm for PdNP. The catalytic behavior of PdNP/AuNAE has been studied using amperometry and voltammetry which showed a linear response up to 2 mM of H2O2 with a sensitivity of 530 mu A mM(-1) cm(-2) at 20 degrees C. This electrode can detect 5 mu M (S/N = 3) of H2O2 at normal conditions without using any enzyme or mediator. A high selectivity toward H2O2 (up to 97%) has been obtained using this electrode platform in the presence of common electrochemical interferences such as ascorbic acid, uric acid, acetaminophen and dopamine. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.010212jes] All rights reserved.