We report an electrochemically prepared 3-mercaptopropionic acid (MPA) capped Pt nanoparticles-Polypyrrole (PPy) nanocomposite film based bioelectrode for the detection of human C-reactive protein (alpha CRP). The electrochemical deposition provides homogeneous distribution of ultrafine Pt(MPA)-NPs within the uniform and adherent PPy film with high degree of geometrical conformity and controllable film thickness. Protein antibody, Ab-alpha CRP, was covalently immobilized through the site specific carboxyl groups of Pt(MPA)-NPs within the polymer nanocomposite film by carbodiimide coupling reaction. The bioelectrode interfacial surface electron transport study towards protein antigen, Ag-alpha CRP, was carried out by electrochemical impedance spectroscopy (EIS). The value of 'n', a Constant Phase Element exponent used as a gauge of the heterogeneity, for Pt(MPA)-PPy nanocomposite film was found to be 0.88 similar to 1 which is indicative of a homogeneous morphology of the composite film with minimal defects. The EIS of the bioelectrode exhibited significant changes in charge transfer resistance (R-et) component at a low ac frequency of <20 Hz towards Ag-alpha CRP detection over a linear range of 10 ng mL(-1)-10 mu g mL(-1) in PBS with a sensitivity of 109.74 Omega cm(2) per decade. (C) 2014 Elsevier Ltd. All rights reserved.