The oxidation behavior of SiC powders was studied using a thermogravimetric analysis (TGA). The effects of temperature (910-1010 A degrees C), particle size (120 nm, 1.5 mu m), and the initial reactant mass on the oxidation behavior of SiC were investigated. Kinetics analysis showed that intra-particle diffusion and chemical reaction controls the oxidation rate. Moreover, a new kinetics model was proposed to describe the oxidation rate of where all diffusion steps (bulk, inter- and intra-diffusion) and the chemical reaction may affect the overall reaction rate. The model was validated through a comparison with the experimental results obtained from the oxidation of SiC powders in TGA experiments. It was found that during the experiments, inter diffusion must also be taken account to describe adequately the oxidation rate. Numerical analysis indicated that inter-particle diffusion has a significant effect on the oxidation rate, especially for larger system.