In the first part of this research, the effect of particle size (35-100 mesh) on the calcination kinetics of a limestone sample was investigated by thermogravimetric analysis technique. Thermal studies showed that two main weight loss regions are observed in limestone samples of different particle size. In the second part of the research, thermal analysis of a medium crude oil sample in a limestone matrix of different particle size is analyzed. Two different reaction regions were observed known as low temperature and high temperature oxidation reactions, respectively. Arrhenius and Coats and Redfern kinetic models were applied to the experimental results and it was observed that the kinetics of crude oil samples of different particles were in the range of 5.4-8.9 kJ/mol in low temperature oxidation and 42.3-74.1 kJ/mol in high temperature oxidation mol depending on the kinetic model and particle size effect.