The catalytic stability of ZSM-5 zeolite in butene aromatization was improved by the treatment of ZSM-5 zeolite with sodium hydroxide solution of appropriate concentration. By characterizing pore structures, the acidity of the catalyst and the coke amount, we found that alkali-treatment of ZSM-5 led to a formation of new mesopores resulting from a preferential removal of silicon species, while the intrinsic micropores remained unchanged. As for the acidity, the amount and properties of acid sites exhibited a slight change on the alkali-treated ZSM-5 zeolites. In addition, the alkali-treatment to ZSM-5 zeolite led to only a little reduction in the amount of coke during the butene aromatization. But a portion of coke was deposited in the newly created mesopores because of the alkali-treatment and the formation of coke in the micropores was found to be reduced. These changes can suppress the channel blockage of ZSM-5 zeolite by the coke deposits during butene aromatization. The variation of the coking location was the main reason for the favorable enhancement in the reaction stability during butene aromatization. (c) 2005 Elsevier B.V. All rights reserved.