Solubility of carbon dioxide in poly(2,6-dimethyl-1,4-phenylene ether) (PPO) and PPO+ polystyrene (PS) blends (25-50 wt.% PPO) was measured at temperatures of 373.15, 427.15, and 473.15 K and pressures up to 20 MPa. The solubility in the blends increased with increasing PPO concentration. The solubility could be correlated with the extended dual mode sorption (EDMS) model in conjunction with Sanchez and Lacombe equation-of-state. The EDMS model correlation estimated a 100 K glass transition temperature depression of PPO by dissolution of carbon dioxide. While Henry's constants for carbon dioxide in the blend polymers in molten state could be satisfied by additivity of the Henry's constant in each pure polymer, the Henry's constants in the glassy state did not show additivity.