Ureaformaldehyde (UF) resin microcapsules doped with TiO2 nanoparticles were prepared by in situ polymerization, and the properties of the microcapsules, such as the surface morphologies, thermal properties, and chemical elemental composition, were measured by optical microscopy, scanning electron microscopy, thermogravimetric analysis, and energy-dispersive X-ray spectrometer analysis. The effects of the presence of ammonium chloride and its concentration and the concentrations of UF resin prepolymer and TiO2 nanoparticles during the reaction and deposition of UF on the microcapsule surface on the properties of the microcapsules were investigated. Enhanced UF resin microcapsules with more stability and mechanical strength could be obtained under the optimal conditions. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012