Microencapsulation is based on multiple emulsion interfacial reaction technique that combines the characteristics of the interfacial reaction and conventional multiple-emulsion processes. In this study, the microcapsules were synthesized with the water-soluble dimethyl methyl phosphorate (DMMP) as the core material and the acetal product of polyvinyl alcohol (PVA) and glutaraldehyde (GA) as the shell material. The microcapsules were characterized by using DSC, IR spectrum and phosphorus qualitative analysis, and the factors affecting microencapsulation were identified and discussed. The data presented herein suggested that the size distribution of microcapsules was affected by the concentration of PVA and SPAN80 and by the phase volume ratio, while the crosslinking agent GA content has little effect. The data also showed that the microcapsules with the core of flame retardant containing organophosphorus would have promising applications in inflaming retarding of cotton fabric. (c) 2006 Wiley Periodicals, Inc.