A series of nanosized [Al]-, [Ga, Al]-, and [Ga]-HZSM-5 catalysts with a fixed Si-to-M3+ ratio (M = Al or Ga) was synthesized by a seed-induced crystallization method. In order to reveal the catalytic nature of the extra framework Ga species, an acid treatment was applied to selectively extract Lewis acidic amorphous Ga cations of as-synthesized catalysts. A comparative evaluation of freshly prepared and acid-treated catalysts in methanol conversion to aromatics showed the dehydrogenative nature of the extra-framework Ga species, which is essential in the enhancement of aromatics. Among tested catalysts, [Ga, Al]-HZSM-5 with a low extra-framework Ga-to-Bronsted acid ratio (0.06) was the most effective. The efficacy is due to the contact synergy of the extra -framework Ga species and the Bronsted acid, by which aromatics originated from the dual cycle mechanism of methanol conversion can be accelerated.