A comparative study has been made on the performance of electrochemical reduction and amperometric sensing of H2O2 by the cathodically and anodically deposited orthorhombic FeS2 thin films. Individual chronoamperometric depositions were carried out on indium doped tin oxide (ITO) coated glass substrates from an aqueous solution containing Mohr's salt (FeSO4(NH4)(2)SO4 center dot 6H(2)O) and Na2S2O3 with optimized molar concentrations. Cyclic voltammetry and linear sweep voltammetry were carried out to determine the exact reduction and oxidation potentials for the two systems. Structural, morphological, compositional, optical and electrical characterizations were carried out using X-ray diffraction (XRD) technique, field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), UV-vis spectroscopy and four-probe and two-probe current-voltage measurements, respectively. It was established from XRD that both cathodic and anodic depositions were orthorhombic (Fe:S=1:2) in nature. Cathodic films were found to have interlinked fiber like morphology, while the anodic films showed flake-like and rough morphology. It was also observed that the amperometric sensing mechanism was highly dependent on the morphology of the deposited films. (C) 2012 Elsevier Ltd. All rights reserved.