Microcapsules were prepared by in situ polymerization technology with poly(urea-formaldehyde) (PUF)-grafted gamma-glycidoxypropyltrimethoxy silane (KH560) copolymer as a shell material and dicyclopentadiene (DCPD) as core materials. The aim was to improve the interfacial bond between microcapsules and epoxy matrix in composites through the epoxy functional group in KH560. The microcapsulating mechanism was discussed and the process was explained. The morphology and shell wall thickness of microcapsules were observed by using scanning electron microscopy. The size of microcapsules was measured using optical microscope and the size distribution was investigated based on data sets of at least 200 measurements. The chemical structure and thermal properties of microcapsules were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectra, and thermogravimetric analysis. Results indicted that the PUF-graft KH560 microcapsules containing DCPD can be synthesized successfully; the epoxy functional group was grafted on the wall material. The microcapsule size is in the range of 40-190 mu m with an average of 125 mu m. The wall thickness of microcapsules sample is in the range of 2-5 mu m and the core content of microcapsules is about 60%. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 1501-1506, 2009