In order to improve stability as well as maintain explosion performance, crystallization of NTO ( 3-nitro-1,2,4-triazole-5-one ), known as a less-sensitive explosive, onto crystal surface of HMX ( cyclotetramethylene tetranitramine ), a very sensitive explosive, were performed by a cooling technique. Nucleation rate and agglomeration rate of NTO on the surface of HMX crystals were measured during crystallization. In secondary nucleation using seed, the supersaturation was found to be the most important parameter during formation of the agglomerated particles. Concentration of HMX seeds and solvent were also found to influence significantly on agglomeration phenomenon. The agglomeration kinetic was correlated with the 3.0nd power of the solution supersaturation and the 2nd power of the number of the suspended particles. The present experimental results suggest that the proposed technique might be one way to reduce the sensitivity of explosive compounds. Key words: crystallization, coating, agglomeration, energetic materials, crystal growth