Polyaniline (PAN) nano-particles, nano-fibrils, and nano-network have been synthesized via electrochemical polymerization of aniline using a three-step electrochemical deposition procedure on alpha-alanine (ALA)-monolayer functionalized glassy carbon electrode (GCE). The structure and properties of PAN nano-structures have been characterized using field emission scanning electron microscope (SEM), Fourier transform infrared spectra (FT-IR), and electrochemical techniques. The 3-dimensional (3D) PAN nano-network/ALA composite film coated GCE (PAN-ALA/GCE) leads to the direct electrochemistry of horse heart cytochrome c (Cyt c) immobilized on this electrode surface. The immobilized Cyt c maintains its activity, showing a surface-controlled electrode process with the electron transfer rate constant (k(s)) of 21.9s(-1) and the charge-transfer coefficient (alpha) of 0.37, and could be used for the electrocatalytic reduction of hydrogen peroxide (H(2)O(2)). The steady-state current response increases linearly with H(2)O(2) concentration from 2.5 x 10(-5) to 3.0 x 10(-4) moll(-1). The detection limit (3delta) is 8.2 x 10(-6) moll(-1).