The conversion of methanol to hydrocarbons over ZSM-5 zeolite catalyst exists within the framework of obtaining gasoline fuel and high-value petrochemicals such as propylene sustainably from bio-feedstock. The initial steps of the reaction are highly debated as methanol and its derivative, dimethyl ether (DME), compete for catalytic sites onto which they could bond within the ZSM-5 zeolite. The objective of this work is to understand how the movement of methanol and DME within the pores of the zeolite affects this bonding process. We aim to quantify and compare the mobility of methanol and DME in ZSM-5 with different acidic site densities (Si/Al = 36 and 135). The experimental data obtained will further be quantitatively analysed to decouple the processes of bonding and release from the active sites. This is required to understand and predict the behaviour of ZSM-5 zeolite catalysts.