The present proposal suggests the use of INS to characterize the acidity of zeolite LTA through the vibrational properties of the different types of hydrogens present as Brønsted acid sites, Si-O(H)-Al. Thus, catalytic properties of the zeolite can be defined.In this project we propose to study the adsorption processes of other small base molecules. CD4 and ethene, that have been chosen because CO (used in previous experiment) lies between these two bases on a scale of basicity (basic properties increase in the row (CD4, CO, CD2=CD2).We propose adsorbing CD4 or CD2=CD2 on a series of LTA zeolites with different Al contents (i.e. acid site concentrations). LTA zeolites with Si/Al ratios of 2, 5 and 40 will be selected and two different adsorbate (CD4 or CD2=CD2) concentrations will be studied.As we did before, in this study we will also concentrate on certain vibrations of low energy associated to the hydrogens in the zeolite.