A novel electrochemical sensing platform (ESP) for nitrobenzene (NB) has been developed using palladium nanoparticles decorated polymer-silica nanocomposite (represented as Pd-GG-g-PAM-silica). The polymeric part of the nanocomposite is based on a biodegradable copolymer, guar gum grafted polyacrylamide (GG-g-PAM). The nanocomposite is characterized by spectroscopic, microscopic and electrochemical methods. Pd-GG-g-PAM-silica efficiently catalyzes the electro-reduction of NB. The mechanism and kinetic parameters of the electrocatalytic reduction of NB at Pd-GG-g-PAM-silica modified glassy carbon electrodes (GCE) are evaluated in 0.1 M phosphate buffer solution (pH 7.0) using linear sweep voltammetry, differential pulse voltammetry and chronoamperometry. The observed electrochemical responses at Pd-GG-g-PAM-silica modified GCE exhibit excellent analytical performance for NB detection with high stability, reproducibility, and acceptable selectivity. This novel ESP exhibit a detection limit of 0.06 mu M with two linear calibration ranges from 1.0 to 1900 mu M and from 1900 to 3900 mM for NB. The diffusion coefficient and catalytic rate constant for NB reduction at the Pd-GG-g-PAM-silica modified GCE is calculated to be 3.88 x 10(-6) cm(2)s(-1) and 1.82 x 10(4) M(-1)s(-1) respectively. In addition, the material is successfully used for the determination of NB in real water samples and the recoveries of the spiked NB are quite satisfactory. (C) 2014 Elsevier Ltd. All rights reserved.