This study focuses on structural and photocatalytic degradation of olive mill wastewater (OMW) of TiO2 supported sepiolite catalysts, prepared by a sol-gel method in aqueous solution. To get the TiO2/Sep nanoparticle, the nanocrystalline TiO2 anatase phase on sepiolite was obtained using a sufficient thermal treatment by gradually increasing the temperature from 300, 400 and 500 degrees C with 1 h intervals for a total of 3 h. Then, the structural features of TiO2/Sep materials were investigated by using different spectral and technical structural analyses with scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA). XRF and X-ray diffraction (XRD). The photocatalytic degradation of TiO2/Sep materials has been investigated in OMW by using ultraviolet (UV), hydrogen peroxide (H2O2) and TiO2/Sep nanoparticles together. The influence of pH, catalyst amount and temperature was investigated in all the experiments and the degradation ratios were found to be strongly influenced by all investigated parameters. The photocatalytic degradation of lignin and phenol was favorable at pH 9-11.0. Optimum values of catalyst dose and temperature were found to be 0.25 and 0.50 g L-1 and 318K, respectively. In addition, the pseudo-first order model was applied and r(2) values were noted from 0.90 to 0.99. (C) 2010 Elsevier B.V. All rights reserved.