A cluster model for Zn/ZSM-5 zeolite is proposed, which consists of an oxygen-bridged [Zn-O-Zn](2+) moiety attached to two framework aluminum ions of two adjacent ZSM-5 5-rings. Its stability and catalytic activity in ethane dehydrogenation were considered using the DFT method and compared with those for single Zn2+ ions in the same rings. It is shown that the oxygen-bridged Zn2+ pair is rather reactive towards ethane dissociation and that the rate-limiting step is release of hydrogen.