The main objective of this study was to investigate the factors that influence the oxidation rate of large (five to eight millimeters in diameter) coal and char particles. To accomplish this, experiments were performed in which the gas temperature, gas velocity, particle size, partial pressure of oxygen, and total pressure were varied. The experiments were performed with the cantilever balance attachment and the high pressure controlled profile reactor. Approximately 90 combustion experiments were performed with Pittsburgh, Utah Blind Canyon, and Wyodak-Anderson coal. These experiments were performed at atmospheric pressure with air and varied gas temperature, gas velocity, and particle size. Following the experiments performed with coal, approximately 70 experiments were performed with char made from Pittsburgh coal. These experiments varied all the environmental conditions mentioned above as well as partial pressure of oxygen and total pressure. After the experiments were completed, the data were analyzed and the following conclusions were made. An increase in the partial pressure of oxygen dramatically increased the oxidation rate when the total pressure remained constant. The oxidation rate was only slightly affected when the partial pressure of oxygen was raised by increasing the total pressure. The oxidation rate dramatically decreased when the partial pressure of oxygen was held constant and the total pressure was raised. The oxidation rate noticeably increased when the initial mass of the particle was decreased. The gas temperature and gas velocity did not affect the oxidation rate greatly for the experiments performed with coal. The oxidation rate increased for the experiments performed with char at the high gas temperature and high gas velocity conditions.