This paper presents a numerical investigation of transport phenomena in pyrolyzing ablators using the finite element method, with a focus on high-temperature applications crucial to aerospace engineering. The study aims to model the transient thermal response of composite materials used in high-temperature protection systems (HTPS) by solving the governing equations for mass conservation, momentum, energy, and decomposition in their weak form. These equations are then solved using the finite element method. Numerical simulations are implemented in FreeFem++ software, providing a comprehensive analysis of the system’s dynamics. Model validation is conducted through systematic verification of transient conduction and pyrolysis kinetics, ensuring the accuracy and reliability of the numerical simulations. The results exhibit a high level of agreement with analytical predictions and benchmark problems. Additionally, the formation and growth of char and pyrolysis layers are examined in detail. This work aims to deepen our understanding of the physics of ablation, ultimately enhancing our ability to model ablative composites used in thermal protection applications.