New zeolite materials designated Nu-6(1) and Nu-6(2) having molar compositions expressed by the formula:
wherein R is a monovalent cation or 1/n of a cation of valency n, X is silicon, and/or germanium, Y is one or more of aluminium, iron, chromium, vanadium, molybdenum, antimony, arsenic, manganese, gallium or boron, and H 2 0 is water of hydration additional to water notionally present when R is H and having defined X-ray diffraction patterns, are prepared from a reaction mixture containing X0 2 (preferably silica), Y 2 0 3 (preferably alumina) and a 4,4'-bipyridyl compound. At temperatures of 200°C or higher, Nu-6(1) is converted to Nu-6(2), a useful catalyst for xylenes isomerisation and the like.