Hard coating sols and films were prepared for UV/thermal dual curing. The coating sols were composed of boehmite nanoparticles modified with organosilanes (e.g. methacryloxy-propyl trimethoxy silane, vinyl triethoxy silane, and 3-glycidoxy-propyltrimethoxy silane), a formulated initiator, and an inorganic or organic cross-linker as an additive. With this coating solution, hard coating films with a pencil hardness above 8H and transparency above 90% in the visible light range were prepared on poly(methyl methacrylate) substrates. In addition, the coating solution could be quickly cured in 3 5 min at a temperature of 100 degrees C by UV/thermal dual curing. The effects of the additive and initiator on the hardness and transparency of the resulting films are described. (c) 2007 Elsevier B.V. All rights reserved.