Abstract: This invention relates to a method of dehydrocyclizing aliphatic hydrocarbons to form corresponding aromatic hydrocarbons. According to the invention, a batch of aliphatic hydrocarbons, in the presence of hydrogen at a temperature of 430.degree. to 550.degree. C is passed over a catalyst consisting essentially of a type L zeolite having exchangeable cations of which at least 90% are alkali metal ions selected from the group consisting of ions of sodium, lithium, potassium, rubidium and caesium and containing at least one metal selected from the group which consists of metals of groups VIII of the periodic table of elements, tin and germanium, said metal or metals including at least one metal from group VIII of said periodic table having a dehydrogenating effect, so as to convert at least part of the batch into aromatic hydrocarbons. The aliphatic hydrocarbons preferably contain 6 - 10 carbon atoms.