The oxidation behavior of coke samples derived from Neilburg oil and its asphaltenes at different coking temperatures was examined using thermogravimetric analysis (TGA). A two-coke model was proposed to describe the coke combustion processes. The two-coke model provided a better prediction than the conventional one-coke model, i.e., the classical Arrhenius model, as it matched the experimental data more accurately, especially at lower combustion temperatures. The two coke pseudocomponents might reasonably represent the cokes derived at different coking temperatures, and the two-coke model appeared potentially useful to interpret the coke combustion process and applicable to simulation. Our experimental data suggest that the coke's reactivity was inversely proportional to the coking temperature. With respect to the coke sources, the coke derived from whole oil showed higher reactivity than the one from asphaltenes, although the difference was modest.