Supercritical carbon dioxide is an efficient solvent for adsorptive separations because it can potentially be used as both the carrier solvent for adsorption and the desorbent for regeneration. Recent results have demonstrated an anomalous peak or "hump" in the adsorption isotherm near the bulk critical point when the adsorption isotherm is plotted as a function of bulk density. This work presents new data for the adsorption and desorption of carbon dioxide in the near-critical region on a crystalline, well-structured adsorbent (NaY zeolite). The results indicate a strong affinity for CO2 as well as a significant hump near the critical point. The lattice model previously developed by Aranovich and Donohue is applied to analyze the adsorption.