Electrochemical behavior of ring C of 3-hydroxyflavone (3-HF) has been investigated by cyclic and differential pulse voltammetry, using a glassy carbon electrode (GCE) in different buffer systems. It exhibited a sensitive diffusion controlled anodic peak at 0.70V (vs Ag/AgCl) in a buffer system at pH 2.0. At higher pH, 8.0, while the peak at 0.70 V shifted to 0.41 V, a new peak at 0.8V appeared. Moreover, electrochemical method was applied to investigate the antioxidant effect and metal chelating properties of 3-HF with Cd2+, Cu2+, Hg2+ and Pb2+ as they could have possible toxicological effects, for which fluorescence technique were also applied. Antioxidant effect was determined in terms of trolox equivalent antioxidant capacity (TEAC) using the peak areas of cyclic voltammetry (CV), which indicated that 1.0 mM 3-HF is equivalent to 0.2 mM of trolox. Such a result might be another indication of the importance of hydroxyl groups on the other rings of flavones. Electrochemical and fluorescence spectroscopic methods revealed that the best interactions of the cations could be obtained depending on the pH of the medium. Selective interactions of Cd2+ and Cu2+ at pH 2 and 7, respectively, were observed. (C) 2010 Elsevier Ltd. All rights reserved.