The degradation of polymer matrix composite material during carbonization and the processing temperature are some important deciding factors to evaluate the performance of carbon–carbon composite (CC) for the targeted applications. In present study, the carbonization of material at the temperature range of 1200–1500 °C is considered as a critical step for understanding the material performance, as it is essential for the progress in the processing of CCs. The heat, mass and momentum transport equations are used with weight loss kinetics to develop a numerical simulation model for the carbonization process. Afterward, to solve the governing equations, a 2-D finite difference method (FDM) is employed. Using material properties, the developed numerical model predicts the distribution of pressure, porosity, density, specific heat, thermal conductivity as a function of surface temperature for square samples of various thicknesses at different heating rates. The comparisons of the results of the 2-D model are carried out with results of 1-D FDM model published earlier.