An article with organic/inorganic composite coating formed, wherein the organic/inorganic composite coating is composed mainly of silica and will not be detached from the base material after Taber's abrasion resistance test prescribed in Japanese Industrial Standards (JIS) R 3212. This composite coating can be formed by a sol gel process from a coating liquid containing a hydrophilic organic polymer. In this liquid, for example, the amount of silicon alkoxide in terms of SiO2 concentration exceeds 3 mass%. When a phosphorus supply source is contained, the mass molarity of proton is in the range of 0.0001 to 0.2 mol/kg, and the molar amount of water is at least 4 times the total molar amount of silicon atoms contained in the silicon alkoxide. According to this sol gel process, there can be obtained a coating excelling in mechanical strength without the need to heat the base material to temperature higher than 400 DEG C and even when the coating thickness is as large as over 250 nm.