As part of an on-going industrial/academic collaboration in to the application of neutron spectroscopy to probe commercially relevant zeolites, this proposal seeks to use the MAPS spectrometer to speciate and quantify the Brønsted acid site distribution of two samples of ZSM-5 and one reference zeolite (silicalite-1). Whereas IR spectroscopy has for many years played a significant role in identifying acid site distributions in zeolitic catalysts, it cannot be reliably used to quantify these sites. Previous work by the applicants has exploited the quantitative nature of INS to determine hydrogen retention in Fe and Ni based catalysts; it is opportune to apply such technologies to add further colour and impact to the current programme on ZSM-5 catalysts.