The electrochemical behavior of p-sulfonated calix[4]arene was studied. In aqueous solution, p-sulfonated calix[4]arene can be oxidized when the potential is more than 0.7 V versus SCE. It is confirmed that the reaction is an irreversible two-electron transfer electrochemical reaction. The anodic peak potential, E-p, is affected by the acidity of the solution. E-p shifts in the negative direction when the pH increases. The electron transfer coefficient, alpha, is 0.65. At 25 degreesC, the diffusion coefficient of p-sulfonated calix[4]arene is 3.1 x 10(-5) cm(2) s(-1). The activation energy, E-a, for the electrochemical reaction is (18.8 +/- 0.2) kJ mol(-1). (C) 2004 Elsevier B.V. All rights reserved.