Adsorption behaviors of the isomeric mixture of 2,6- and 2,7-dimethylnaphthalene (DMN) (two-component systems) dissolved in supercritical carbon dioxide using NaY-type zeolite as the adsorbent were studied. The experiments were performed at the temperature 318.2 K and the pressures 12.0, 14.8, and 19.8 MPa. By comparison with the previous results (Iwai, Y.; et al. Ind. Eng. Chem. Res. 1994, 33, 2157) at temperature 308.2 K and the pressures 12.0, 14.8, and 19.8 MPa, the effects of temperature and pressure on the adsorption behaviors were examined. it was shown that the higher separation efficiency, the lower adsorption amounts, and the shorter breakthrough times for both 2,6- and 2,7-DMN were obtained at higher pressure or lower temperature. The adsorption behaviors of 2,6- or 2,7-DMN (single-component systems) dissolved in supercritical carbon dioxide at the temperature 308.2 K and the pressure 14.8 MPa were also measured in order to compare with their behaviors for two-component systems. Moreover, the experimental breakthrough curves obtained for all systems were correlated by a model using an overall mass-transfer coefficient by assuming a linear adsorption equilibrium. The overall mass-transfer coefficients of 2,6- and 2,7-DMN were estimated by use of the external fluid film mass-transfer coefficients and the intraparticle mass-transfer coefficients predicted. The model gave good correlation results for the all experimental breakthrough curves.