The invention concerns a solid crystalline designated COK-7, which has a particular X ray diffraction diagram. Said solid has a chemical composition, expressed on an anhydrous base in terms of moles of oxides by the formula XO.sub.2: mYO.sub.2, X representing one or more tetravalent element(s), Y representing at least one trivalent element. The invention also concerns a process for preparing said solid and the use of said solid in hydrocarbon transformation.