A simple strategy to fabricate an efficient electrochemical sensor for epinephrine (EP) oxidation is developed by selective etching of the electrodeposited thin Au-Ag alloyed film. The electrochemical characterization of obtained nanoporous spongelike Au-Ag electrodes was carried out by cyclic voltammetry (CV) and chronoamperometry. It was found that the nanoporous Au-Ag electrode exhibits a significantly higher electrocatalytic activity toward EP oxidation when comparing with a bulk Au electrode. The performed electrochemical tests demonstrated that EP oxidation and reduction processes are controlled by diffusion. The transfer coefficient (alpha = 0.55) and total number of electrons involved in the anodic oxidation of epinephrine to adrenalinequinone (n = 2) as well as the diffusion coefficient of EP in the 0.1 M phosphate buffer solution PBS (D = 1.29 x 10(-5) cm(2) s(-1)) were evaluated. Using chronoamperometry, the average catalytic rate constant was calculated to be 2.16 x 10(5) M-1 s(-1). Under the optimized conditions, the electrochemical sensor exhibited a linear response for EP concentration over the range of 25-300 mu M for linear sweep voltammetry (LSV), 10-100 mu M for differential pulse voltammetry (DPV) and 25-700 mu M for chronoamperometry. The DPV method has the highest sensitivity (1.52 mA cm(-2) mM(-1)) and the lowest detection limit (5.05 x 10(-6) M). (C) 2015 Elsevier B.V. All rights reserved.