A microencapsulation process with in-situ polymerization has been studied by using an anionic water-soluble polymer for microencapsulated phase change materials. As the phase change material inside capsule wall adsorb a large quantity of heat when it changes from solid to liquid state, it is very useful for the enhanced thermal management such as heat transport and storage. The condensation reaction of MF pre-condensate followed by emulsification is initiated by lowering the pH of the emulsion. As the portion of MF precondensate is increased in the extermal medium with the reaction step, the majority of the MF condensate around the internal phase droplet to form thick, hard microcapsule wall. In this study, we have found that the various condition in microencapsulation process with MF by in situ polymerization affects on the characteristics of products.