The adsorption of alkaline salts of ethylenediaminetetraacetic acid (EDTA) on inorganic supports characterized by the different value of the isoelectric point of the surface (IEPS) has been investigated by transmission and photoacoustic (PA) FT-IR. The IR spectra in the 1800-1200 cm(-1) region of the supported complexones are different from those of the unsupported compounds. The results obtained imply that the observed changes in the properties of adsorbed complexones are mainly due to interaction of the carboxyl groups of chelate molecule with inorganic oxide hydroxyl groups. The models of those interactions have been proposed. The IEPS value has a noticeable influence on the nature of the interactions observed. Based on the experimental data the ability of inorganic oxide interaction with the chelate molecule can be presented as follows: V2O5 < SiO2 < TiO2 < MgO < Al2O3 < ZrO2-La < ZrO2 (c) 2005 Elsevier B.V. All rights reserved.