Calixarene molecules of calix[4]arene and calix[4]arene diquinone disulfide (CDS) have been investigated in aqueous HClO4 solution by using cyclic voltammetry and scanning tunneling microscopy (STM). The two molecules are found to organize ordered arrays on a Au(111) surface. High-resolution STM images reveal the molecular orientation and packing arrangement in the two ordered adlayers. Calix[4]arene molecules form butterfly shaped dimers through OH groups, and adsorbed at Au(111) surface via phenolic groups. CDS molecules are upright on the electrode surface through the lower rim groups. The structural models are proposed for the two adlayers. (C) 2002 Elsevier Science B.V. All rights reserved.