The present invention relates to new methods of making crystalline materials isostructural to ITQ-21, as well as to new crystalline materials obtainable by such methods, and their use in hydrocarbon conversion processes. In one of its aspects, the invention relates to a method of making a crystalline material iso-structural to ITQ-21, the method comprising: (a) providing a synthesis mixture comprising water, at least one source of germanium, at least one source of a tetravalent element X other than germanium, at least one structure directing agent R, optionally at least one source of trivalent element Y and optionally at least one source of fluoride, wherein the structure directing agent R is a compound of formula C.sup.1C.sup.2R.sup.1R.sup.2N.sup.+A.sup.-(I), in which C.sup.1 and C.sup.2 each independently represent a substituted or unsubstituted cyclohexyl or cyclopentyl group, R.sup.1 and R.sup.2 each independently represent a methyl group, an ethyl group or a propyl group, or R.sup.1 and R.sup.2 together with the nitrogen atom they are connected to form a ring containing 5 or 6 atoms, and A represents hydroxyl, fluorine, chlorine, bromine or iodine, (b) forming said crystalline material from the synthesis mixture; (c) recovering said crystalline material.