A novel crystalline aluminosilicate which exhibits a specific X-ray diffraction pattern having at least seven diffraction lines showing the following relative intensities at the positions of the following respective diffraction angle (2.theta.):______________________________________ Diffraction angle (2.theta., deg) Relative intensity ______________________________________ 7.8 .+-. 0.2 5-30 8.7 .+-. 0.2 90-100 8.9 .+-. 0.2 90-100 17.5 .+-. 0.2 5-30 17.7 .+-. 0.2 5-30 23.1 .+-. 0.2 30-80 23.3 .+-. 0.2 20-50 ______________________________________ Such a crystalline aluminosilicate is produced by the mutual reaction of the components of a mixture of a silica source, an alumina source, a sodium source and water in the presence of 1,8-diamino-4-aminomethyloctane. The crystalline aluminosilicate thus prepared has an excellent catalytic activity and exhibits a specific adsorption behavior. The novel crystalline aluminosilicate according to the present invention may be advantageously used as a catalyst for producing a disubstituted benzene from a monosubstituted benzene or for producing a lower olefin from methanol and/or dimethyl ether and as an adsorbent.