Polyurea microcapsules containing pesticide (Dursban trade name for O,O-3,5,6-trichloro-2-pyridyl phosphorothioate, C9H11C13NO3PS) as an active agent were prepared by reaction of polyisocyanate (such as toluene diisocyanate) and polyamine (such as diethylene triamine) as the monomers. The first step gives rise to the formation of oil-in-water emulsion, this is followed by initiation of polymerization process to produce polyurea capsule wall. It has been found that the microcapsule formation depends on temperature, type and amount of emulsifier, co-emulsifier, matrix forming agent, stirring speed, organic phase, etc. This paper is devoted to the studies of above factors that optimize the formation of microcapsules wall. Formation of polyurea was confirmed by F-I-IR technique and the thermal behaviour of polyurea microcapsules was investigated by differential scanning calorimetery method. The morphology of microcapsules was studied by scanning electron microscope.