Electrochemical oxidation of L-ascorbic acid on polycrystalline silver in alkaline aqueous solutions is studied by cyclic voltammetry (CV), chronoamperometry (CA) and impedance spectroscopy (IS). The anodic electro-oxidation starts at -500 mV versus SCE and shows continued anodic oxidation in the cathodic half cycle in the CV regime signifying slowly oxidizing adsorbates. Diffusion coefficient of ascorbate ion measured under both voltammetric regimes is around 1.4 x 10(-5) cm(2) s(-1). Impedance spectroscopy measures the capacitances associated with double layer and adsorption around 50 mu F cm(-2) and 4 mF cm(-2) as well as the adsorption and decomposition resistances (rates). (C) 2009 Elsevier B.V. All rights reserved.