The manganese hexacyanoferrate (MnHCF) mixed-valent poly(3,4-Ethylenedioxythiophene) (PEDOT) hybrid film (MnHCF-PEDOT) was prepare on glassy carbon electrode by multiple scan cyclic voltammetry. These materials are characterized using atomic force microscopy (AFM), field emission scanning electron microscope (FE-SEM), energy dispersive spectroscopy (EDS), x-ray diffraction studies (XRD) and electrochemical impedance studies (EIS) techniques. The advantages of these films are demonstrated for detection of catechin and melatonin using cyclic voltammetry and amperometric. The electrocatalytic oxidation of catechin and melatonin at different electrode surfaces such as the bare GCE, MnHCF/GCE and MnHCF-PEDOT/GCE modified electrodes was explored in 0.1 M KCl solution at pH 1.5.The electrochemical sensor for catechin and melatonin exhibited a wide linear response range (0.1 to 4.4 M, R2 = 0.9965 for catechin and 0.1 to 4.6 mM, R2 = 0.9998 for melatonin), lower detection limit (0.01 mM) and fast response time (3 s).In addition, the MnHCF-PEDOT/GCE exhibited a distinct advantage of simple preparation, specificity, stability and reproducibility.