An ultra-sensitive method based on the electrodeposited polymer nano-composite using amino functionalized graphene oxide (EAGO) and conductive polymer (poly 4-amino-3-hydroxy-1-naphthalenesulfonic acid; p-AHNSA) for the determination of atenolol (ATN) is presented. The surface morphology of the polymer nano-composite has been investigated by using Cyclic voltammetry (CV), Square wave voltammetry (SWV), Electrochemical Impedance Spectroscopy (EIS), Field Emission-Scanning Electron Microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR) and Powder X-ray diffraction (XRD). The oxidation of ATN occurred in a well-defined, pH dependent peak. The polymer nano-composite modified surface electro-catalyzed the electrochemical oxidation of atenolol in comparison to the unmodified surface and GO/p-(AHNSA) modified surface. The determination of atenolol was carried out in the wide concentration range and a linear calibration plot was observed in the range 0.1-300 mu Mwith sensitivity and detection limit (L.O.D.) of 01334 mu A M-1 and 20 nM (n = 3), respectively. The analytical applicability of the developed method has been demonstrated in detecting ATN in the pharmaceutical formulations and biological fluids (urine and plasma) with excellent recoveries of > 97%. (C) 2016 The Electrochemical Society.