The nominal stoichiometric CaCu3Ti4O12 were modified into nonstoichiometric Ca(1+x)Cu3Ti(4-x)O12-2x (0.02 ≤ x ≤ 0.10), were synthesized by using conventional solid state method. The ceramic samples were mixed in acetone media and dried in the oven. The thermal properties of the prepared samples were analyzed by using Thermogravimetry Analysis (TGA) and Differential Scanning Calorimetry (DSC). The thermal behavior of the samples was investigated as a function of measured both Ca and Ti content altered in CCTO. The influence of these thermal properties of CCTO materials can be a new finding to understand future study for the CCTO crystallization and fusion reaction. The results showed that the mass loss of the samples was drastically dropped (6.68% - 7.45%) at a temperature around 714 °C to 785 °C at the first stage, then decreased moderately (2.65% - 3.15%) at a temperature around 890 °C to 960 °C for the second stage. This is due to the oxygen absorption decreased and the reduction of the single phase of CCTO. Meanwhile, the DSC pattern showed 2 endothermic peaks at ~765 °C and at ~936 °C which related to the melting point and crystalline phase of the sample changes.