The sorption and transport properties of carbon dioxide gas in cellulose (CELL) poly(vinyl alcohol) (PVA), and three miscible blends containing 30, 50, and 70 wt percent CELL were investigated at pressures up to 1 atm at 25 degrees C. The sorption isotherms exhibit Henry’s law behavior. The solubility, diffusion, and permeability coefficients are all lower than expected from the simple semilogarithmic additivity rule. The various results are interpreted in terms of theories which have been proposed to describe gas sorption and transport in miscible blends, and the sorption and transport coefficients are correlated in terms of blend composition.