Mo/HZSM-5 catalyst with highly dispersed MoO (x) species was prepared by adding ammonia solution to the ammonium heptamolybdate aqueous solution during the impregnation process. Compared with the large Mo7O246- species which is predominantly presented in the conventional impregnation solution, the monomer MoO42- formed in ammonia solution could efficiently diffuse into the micropores and/or channels of the HZSM-5, resulting in higher dispersion of Mo species as well as enhanced interaction with the surface -OH groups of HZSM-5. Consequently, the obtained Mo/HSZM-5 catalyst showed rather high catalytic stability and greatly enhanced selectivity towards benzene for methane dehydroaromatization reaction by effectively inhibiting the coke formation.