Abstract: A porous material composed of many SiO.sub.4 tetrahedra sheets having interlayer bridges of SiO.sub.2. It has pores having a diameter of 10 .ANG. or above, and possesses the properties of a solid acid formed by the isomorphous substitution of metal atoms for Si of SiO.sub.4 frameworks. It is made by a process including introducing an organic substance into interlayer space of crystals of layered silicates to expand the spacing between crystal layers, as well as forming bridges of SiO.sub.2 therebetween, bringing the intercalated compounds into contact with a metal salt to link metal atoms to the SiO.sub.4 frameworks, and firing the products. The material can withstand a temperature of 800.degree. C., has a pore diameter larger than that of zeolites, etc., and is useful in making an adsorbent or catalyst for molecules having a high molecular weight, such as a catalyst for the catalytic cracking of petroleum.