The effect of the molecular structure of monosaccharides on their electrochemical behavior at a gold electrode in alkaline medium was investigated in order to elucidate the relation between the structure and electro-reactivity. The oxidation of the aldehyde hydrate (or hemiacetal) at C1 carbon atom is the easiest occurring at E < 0.7 V vs. RHE. The oxidation of the primary alcohol group, assisted by the adsorption of the molecule, takes place at potentials from 0.8 to 1.1 V vs. RHE. Vicinal diols oxidation which leads to the C-C bond cleavage occurs between 1.1 and 1.3 V vs. RHE. The spatial orientation of OH groups has important effect on the oxidation of vicinal diols. (c) 2006 Elsevier B.V. All rights reserved.