CdCu3Ti4O12 (CdCTO) ceramics were systematically synthesized via the sol-gel technique. The optimal CH3COOH and Ti(OC4H9)(4) concentrations in the synthesis solution and processing temperature were found to be 5.0 vol%, 0.50 mol/L and 60 degrees C, respectively. These materials exhibited high densities and fine-grained microstructures along with outstanding dielectric properties, including an er of approximately 1.63 x 10(4) and a tan delta of 0.035 at 10 kHz. Over the temperature range from -55 to 150 degrees C, the temperature coefficients of the dielectric constant at 1 and 10 kHz were -13.9% to 1.20% and -9.10% to 3.92%, respectively, indicating that these ceramics possess excellent thermal stability. These properties also meet the requirements for X8R applications. Data acquired from complex impedance spectroscopy and electrical modulus assessments demonstrates that the superior dielectric properties of these CdCTO ceramics can be attributed to the internal barrier layer capacitor theory (IBLC).