The synthesis of a crystalline material, in particular, a high silica zeolite, comprising a chabazite-type framework molecular sieve is conducted in the presence of an organic directing agent having the formula: [R.sup.1R.sup.2R.sup.3N--R.sup.4].sup.+Q.sup.- wherein R.sup.1 and R.sup.2 are independently selected from hydrocarbyl groups and hydroxy-substituted hydrocarbyl groups having from 1 to 3 carbon atoms, provided that R.sup.1 and R.sup.2 may be joined to form a nitrogen-containing heterocyclic structure, R.sup.3 is an alkyl group having 2 to 4 carbon atoms and R.sup.4 is selected from a 4- to 8-membered cycloalkyl group, optionally, substituted by 1 to 3 alkyl groups each having from 1 to 3 carbon atoms; and a 4- to 8-membered heterocyclic group having from 1 to 3 heteroatoms, said heterocyclic group being, optionally, substituted by 1 to 3 alkyl groups each having from 1 to 3 carbon atoms and the or each heteroatom in said heterocyclic group being selected from the group consisting of O, N, and S, or R.sup.3 and R.sup.4 are hydrocarbyl groups having from 1 to 3 carbon atoms joined to form a nitrogen-containing heterocyclic structure; and Q.sup.- is a anion.