The present invention provides a coating composition, which can simply produce a porous siliceous film having excellent mechanical strength and, at the same time, possessing a stable very low level of dielectric and good chemical resistance to various chemicals, and to provide a process for producing a siliceous material using the same. The coating composition according to the present invention comprises a polyalkylsilazane compound, an acetoxysilane compound, an organic solvent, and, if necessary, a pore forming material. The present invention also provides a siliceous material produced by firing the coating composition and a process for producing the same.