CaCu3Ti4O12 (CCTO) thin films with various thicknesses were prepared by a sol-gel multiple coating processes on Pt/Ti/SiO2/Si substrates. Microstructures and surface morphologies of CCTO thin films were analyzed by grazing incident X-ray diffractometer (GIXRD) and scanning electron microscope (SEM), respectively. The correlation between the thickness and electrical properties of CCTO films was investigated. The dielectric constants of CCTO films decreased with increasing film thickness (coating cycle). Both the dielectric constant of CCTO films and interlayer are calculated. Possible mechanisms are explored to explain the thickness dependence of the dielectric constant of CCTO films. (C) 2007 Elsevier B.V. All rights reserved.