The effect of additive and pretreatment condition on the activity and stability of Mo/HZSM-5-based catalysts for methane non-oxidative transformation to aromatics and Ct hydrocarbons is investigated. Activity and selectivity of Mo/HZSM-5-based catalysts can be modified by the addition of a second metal component, and the catalytic performance of the catalyst is very sensitive to the atmosphere of pretreatment at high temperature. High methane conversion of over 10% and quite stable activity have been obtained at a reaction temperature of 973 K over Mo/HZSM-5, Mo-W/HZSM-5 and Mo-Zr/HZSM-5 catalysts pretreated by air at a temperature of 873 K. Catalyst pretreatment under air atmosphere at high temperature may lead to an increase in the pore size of the catalysts and a decrease in methane conversion and activity maintenance. However, the catalysts can be stabilized if they were pretreated under an atmosphere of methane. A new Mo phase may be formed on the catalysts under methane atmosphere, which is a prerequisite for the formation of aromatics and C-2 hydrocarbons.