N-heptane cracking has been carried out on MCM-22, and its kinetic and decay behaviour is compared with that of ZSM-5 and Beta zeolites. In the case of MCM-22 cracking occurs in the 10-member ring channel system, as well as in the large cavities formed by 12-member rings. Product selectivities show that MCM-22, while presenting features which indicate structural similarities with ZSM-5, it also presents characteristics corresponding to pores or cavities larger than ZSM-5. The selectivities to the individual products together with C-1 + C-2/iC(4), C-3/C-4, C-5/C-2, iC(4)/total C-4, and alkane/alkene ratios indicate that MCM-22 has good properties to be used as an FCC octane booster additive specially valuable for the production of reformulated gasolines.