Zirconium oxide materials (loped with transition metals (Mn, Fe, Co, Ni and Cu) were synthesized using sol-gel methods. The powders, which were obtained, were characterized by XPS, XRD, UV-vis spectroscopy and nitrogen adsorption. The photodegradation of 2,4-dichlorophenoxyacetic acid (2,4-D), a herbicide used in agricultural applications, was used as a test reaction to study the activity of the compounds synthesized. Photodegradation studies were performed using a lamp radiating light with a UV wavelength of 254 nm. Characterization studies showed a predominance of the tetragonal phase of zirconium oxide for all of the samples studied. The values obtained for the forbidden energy level E-g fall in a range between 3.6 and 5.5 eV. BET surface areas were found to be in a range between 55 and 80 m(2)/g. The concentration of the metals is small and in the case of Ni it could not be detected. Samples calcined at 400 degrees C used in the photocatalytic study showed the highest activity. Mn/ZrO2 was the most active photocatalyst used. A 70% conversion of 2,4-D was obtained in the first hour. This can be compared to a conversion of only 30% in the absence of Mn/ZrO2. (c) 2007 Elsevier B.V. All rights reserved.