UV-Curable nanocomposites were prepared by the in situ photopolymerizaton with nanosilica obtained from sol-gel process. The photoinitiator 2-hydroxy-2-methyl-1-phenylpropane-1-one (1173) was anchored onto the surface of the nanosilica with or without methacryloxypropyltrimethoxysilane (MAPS) modification. The photopolymerization kinetics was studied by real-time Fourier transform IR (RTIR), and the microstructure and properties of the nanocomposite were investigated Using transmission electron microscopy and UV-visible (UV-vis) transmistance spectra. RTIR analysis indicated that the nanocomposites without MAPS had higher curing rates and final conversion than those with MAPS. The nanocomposite,; with an uniformal dispersion of nanosilica had high UV-vis transmittance. (c) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 1936-1941, 2009