Silicon nitride was formed by nitriding acid-leached and pyrolyzed rice husk in a nitrogen atmosphere. The nitridation kinetics of the pyrolyzed husk pellet over a temperature range of 1473-1723 K were studied by a thermal gravimetric analysis (TGA) technique. The effects of gas flow rate, pellet size, pellet-forming pressure, initial grain sizes, and temperature on the extent of nitridation were examined extensively Experimental results showed that the nitridation rate of the pyrolyzed husk pellet was distinctly faster than the conventional C/SiO2 mixture process. The rate expressions of the nitridation of the pyrolyzed husk pellet were determined. The activation energy was found to be 115+/-1kJ/mol. The reaction was mainly controlled by the diffusion of the gaseous reactant through the product layer. A kinetic model of the nitridation process was developed, and it gave good agreement with the experimental results.