HMX (cyclotetramethylene tetranitramine) was coated with NTO (3-nitro-1,2,4-triazole-5-one) by solution crystallization. Two-step coating crystallization was investigated to enhance coating morphology. The first coating process using HMX seed and the second coating process using HMX coated with NTO obtained from the first process were compared in terms of coating shape, coating surface, nucleation rate, metastable zone width, and interfacial energy. The objective of this study was to examine how operating conditions affected the surface morphology by coating crystallization. The parameters such as type of seed, concentration, and cooling rate were used in the crystallization process. Finally, the second coating process was found to achieve compact and uniform surfaces of NTO crystals coated on the HMX surface. It was found that higher supersaturation enhances cluster aggregation, which results in uniform coating on the HMX surface.