The present work describes the development of a polyaniline/polyaniline-2-sulfonic acid/reduced graphene oxide composite (PANI/SPANI/rGO) modified electrode by electropolymerization to detection of hydrogen peroxide. The ionic transport at the PANI/SPANI/rGO film was evaluated by the investigation of the protonic and anionic participation in the charge compensation processes. The sulfonic group and reduced graphene oxide in the composite film contribute to suppression of the anionic transportation and improve the composite ability to fixing cytochrome c redox protein (Cytc). The ability of the PANI/SPANI/rGO film in absorbing the Cytc resulted in a high sensitivity (0.45 mu A L mu mol(-1)), high linear range (from 0.1 mu mol L-1 up to 1000 mu mol L-1) and low limit of detection (0.04 mu mol L-1) to hydrogen peroxide. Indeed, the hybrid organic-inorganic sensor exhibited a good reproducibility and stability to H2O2 reduction at an applied potential of -200 mV vs. Ag/AgCl. (C) 2015 Elsevier B.V. All rights reserved.