This research was focused on the combustion kinetics and oxidation mechanisms of light crude oils in limestone and sandstone matrices. Similarity of the TGA-DTA curves was produced for different crude oils + limestone or sandstone mixtures indicates that the crude oil undergoes three major transitions, known as low-temperature oxidation, fuel deposition, and high-temperature oxidation when subjected to an oxidizing and constant rate environment. Kinetic analysis of the low- and high-temperature oxidation regions was performed using the ASTM and Arrhenius kinetic methods. In reaction mechanism of the combustion reactions, oxidation mechanisms, and rate-controlling steps of fluid-solid reactions in limestone matrix was also determined. It was observed that the linear behavior at elevated temperatures justifies the assumption that chemical reaction was the controlling step.