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Adsorption of supercritical CO₂ in nanoporous silica aerogel was investigated by a combination of experiments and molecular-level computer modeling. High-pressure gravimetric and vibrating tube densimetry techniques were used to measure the mean pore fluid density and excess sorption at 35 and 50 °C and pressures of 0–200 bar. Densification of the pore fluid was observed at bulk fluid densities below 0.7 g/cm³. Far above the bulk critical density, near-zero sorption or weak depletion effects were measured, while broad excess sorption maxima form in the vicinity of the bulk critical density. The CO₂ sorption properties are very similar for two aerogels with bulk densities of 0.1 and 0.2 g/cm³, respectively. The spatial distribution of the confined supercritical fluid was analyzed in terms of two nanodispersed phases with sorption- and bulk-phase densities and their volumes by means of the adsorbed phase model …