ABSTRACT: The adsorption of ethylene over microcrystal beta zeolites was studied at 70 °C using the reversed-flow inverse gas chromatography (RF-IGC). This method, based on the monitoring of concentration in time resolved allow to follows the surfaces coverage and the adsorption sites occupation depending on the adsorption energies. A pristime crystals were synthetized to rule the effect of surface defects. Therefore, the adsorption take place mainly on the BrØnsted sites. The textural and acidic properties were modified to show the impact of porosity and acidity on the surface coverage and the nature of the interactions. At 70 °C, the presence of porosity doesn’t affect a lot the coverage surface while the acidity induce a second adsorption phase. The stronge interactions are visible only in the presence of the BrØnsted sites. These sites also has an influence on the lateral interactions. Indeed, the increase in the BrØnsted acidity involves an increasing in strong lateral interactions measured with the RF-IGC.