Nanosized ZSM-2 zeolite with crystal size of similar to 100 nm was synthesized and ion exchanged in order to characterize its behaviour in the catalytic degradation of polyethylene (PE) in a semi-batch reactor. The starting ZSM-2 allowed a reduction in the PE degradation temperature of more than 80 C as quantified by dynamic thermogravimetric analysis (TGA). By either proton or Lanthanum exchanges, the nanozeolite increased the acidity improving even more these degradation processes. The starting nanometric catalyst was dramatically more active than a micrometric Y-zeolite displaying lower onset temperatures of PE degradation due to its higher external surface area. These differences nevertheless were reduced by ion-exchanging the Y-catalysts. Our results confirm the relevance of both the zeolite acidity and other parameters, such as crystal size and crystallinity of the zeolite framework, on the catalytic efficiency. Regarding the degradation products during the catalytic process, both zeolites increased the production of low boiling compounds being more efficient the ZSM-2 based catalysts reaching a yield about 90%. Higher amount of accessible sites active for cracking on the external surface of the nanosized crystals would be responsible of this high gas yield. Furthermore, ZSM-2-based zeolites were highly selective to propylene and C4 compounds compared with Y-based zeolites. These results open up the use of nanosized ZSM-2 zeolites in the catalytic degradation of PE with relevant energetic applications. (C) 2010 Elsevier B.V. All rights reserved.