An in-situ polymerization process prepared a series of melamine formaldehyde (MF) microcapsules containing phase change material (PCM) as core material. The phase change temperature of this PCM was 24 degrees C and its phase transition heat was 225.5 J/g. The microencapsulated phase change materials (MicroPCMs) were bedded in indoor-wall materials to store and release heat energy, which would economize heat energy and make the in-door condition comfortable. We investigated the structural formation mechanism by microscope and scanning electron microscopy (SEM). The superficial morphology measurements indicated the optimal shell material dropping rate 0.5 mL min(-1), double-shell, and temperature elevating speed 2 degrees C/10 min. The results obtained in the present investigation were reasonably understood on the basis of getting determinate rigidity and compacted shell. Also, the observed results were used to control the mass of shell material to get desired thickness of shell. (c) 2006 Wiley Periodicals, Inc.