Gallium is incorporated into zeolite H-ZSM-5 by reductive solid-state ion exchange, i.e., by heating a physical mixture of gallium oxide and H-ZSM-5 in a hydrogen flow at 600 o C. The samples are characterized by AES/ICP, XRD, FTIR and MAS NMR spectroscopy. Methylcyclohexane is converted over these catalysts in a hydrogen atmosphere at 6 MPa and 250 to 400 o C, yielding a high-quality synthetic steamcracker feedstock (consisting mainly of ethane, propane and n-butane). Mechanistic aspects of the reaction are discussed, and the importance of non-classical Haag-Dessau cracking is emphasized.