Density of supercritical carbon dioxide (scCO(2)) confined in mesoporous glass is determined at isochoric heating in the temperature range from 30 to 68 degrees C by measuring the Raman shift of a single vibrational band using coherent anti-Stokes Raman scattering (CARS) spectroscopy. The density in the pores appears to be significantly (similar to 30%) higher in the vicinity of the bulk critical temperature and asymptotically decreases at higher temperatures. Similar results have been obtained using two different glass samples with the pore radii of 2 and 3.5 nm. The spectroscopic approach applied here shows potential in precise characterization of supercritical fluid behavior under conditions of nanoconfinement.