A coating composition comprising (A) 100 parts by weight of an organosilicon compound having a hydrolyzable group-bearing silyl group, and (B) 0.1-50 parts by weight of a hydrolytic condensate of a reaction product and/or a mixture of a &bgr;-diketone with a mixture (b-1) of a titanium tetraalkoxide and an alkoxide of Zr, Fe, Al, Zn, In, Cu, Si, Sn, W or Mg. The coating composition is applied to plastic articles, especially of polycarbonate, to endow them with superior transparency, mar resistance, weather resistance, and chemical resistance. The coated articles find use in outdoor applications as windows and windshields on vehicles and building windows.