Process for the preparation of a metal-doped pentasil-type zeolite, which process comprises the steps of: a) preparing an aqueous precursor mixture comprising a silicon source and an aluminium source, at least one of these sources being doped with a rare earth metal dopant or a transition metal dopant of Groups Vb-Vlllb, lb, or lib of the Periodic System, and wherein the aqueous precursor mixture preferably comprises a seeding material, b) thermally treating the precursor mixture to form a metal-doped pentasil-type zeolite, wherein the pentasil-type zeolite is ZSM-5 or ZSM-11, wherein the metal-doped pentasil-type zeolite has a SiO 2 /Al 2 O 3 ratio of 25-90 and contains 0.1-10 wt%, of dopant calculated as oxide and based on the dry weight of metal-doped pentasil-type zeolite, wherein the metal dopant has been incorporated into the silicon and/or the aluminium source before the above process is performed, by preparing the silicon and/or the aluminium source in the presence of the desired dopant or by impregnation or ion exchange of the silicon and/or the aluminium source with the metal dopant, whereby the metal compound is in the silicon or the aluminium source as a metal-doped silicon or aluminium source and not freely present in the aqueous precursor mixture, wherein the metal-doped silicon source is selected from the group consisting of metal-doped sodium (meta)silicate or water glass, metal-doped stabilised silica sols, metal-doped silica gels, metal-doped polysilicic acid, metal-doped tetra ethylortho silicate, metal-doped precipitated silicas, metal-doped SiAl cogels, and mixtures thereof and wherein the metal-doped aluminium source is selected from the group consisting of metal-doped aluminium trihydrate (AI(OH)3), metal-doped thermally treated aluminium trihydrate, metal-doped (pseudo)boehmite, metal-doped aluminium chlorohydrol, metal-doped aluminium nitrohydrol, metal-doped SiAl cogels, and mixtures thereof. a) preparing an aqueous precursor mixture comprising a silicon source and an aluminium source, at least one of these sources being doped with a rare earth metal dopant or a transition metal dopant of Groups Vb-Vlllb, lb, or lib of the Periodic System, and wherein the aqueous precursor mixture preferably comprises a seeding material, b) thermally treating the precursor mixture to form a metal-doped pentasil-type zeolite, wherein the pentasil-type zeolite is ZSM-5 or ZSM-11, wherein the metal-doped pentasil-type zeolite has a SiO 2 /Al 2 O 3 ratio of 25-90 and contains 0.1-10 wt%, of dopant calculated as oxide and based on the dry weight of metal-doped pentasil-type zeolite, wherein the metal dopant has been incorporated into the silicon and/or the aluminium source before the above process is performed, by preparing the silicon and/or the aluminium source in the presence of the desired dopant or by impregnation or ion exchange of the silicon and/or the aluminium source with the metal dopant, whereby the metal compound is in the silicon or the aluminium source as a metal-doped silicon or aluminium source and not freely present in the aqueous precursor mixture, wherein the metal-doped silicon source is selected from the group consisting of metal-doped sodium (meta)silicate or water glass, metal-doped stabilised silica sols, metal-doped silica gels, metal-doped polysilicic acid, metal-doped tetra ethylortho silicate, metal-doped precipitated silicas, metal-doped SiAl cogels, and mixtures thereof and wherein the metal-doped aluminium source is selected from the group consisting of metal-doped aluminium trihydrate (AI(OH)3), metal-doped thermally treated aluminium trihydrate, metal-doped (pseudo)boehmite, metal-doped aluminium chlorohydrol, metal-doped aluminium nitrohydrol, metal-doped SiAl cogels, and mixtures thereof. <EOS>