We revealed that the bare. fluorine doped tin oxide (FM) exhibited the electrocatalytic ability towards the oxidation of glutathione (GSH) in a narrow pH region, which was examined using linear sweep voltammetry (LSV). LSV indicated that an oxidation peak of GSH at the FTO electrode occurs at 027 V (vs. SCE) that is 0.77 V negative of that at the bare Pt electrode, and GSH cannot be oxidized at the glassy carbon (GC) electrode in a potential region -0.40 to 1.20 V, at pH 4.4. On the basis of the electrocatalytic oxidation of GSH in a narrow pH region 4.0-5.5 and its lower oxidation peak potential, the bare FTO electrode can be used as a probe to recognize GSH from the 20 alpha-amino acids present in proteins, cystine, homocysteine, cysteamine, thiobenzoic acid, ascorbic acid, catechol, and dopamine. Its detection limit for the recognition of GSH is 5 nM. (C) 2016 Elsevier B.V. All rights reserved.