The facilitated transport of CO₂ through a hydrophilic polymeric membrane immobilized with K₂CO₃/KHCO₃ buffer solution has been investigated. The reaction of dissolved CO₂ in electrolyzed alkaline solution must consider hydration of CO₂ with water, chemical reaction of CO₂ with OH^- and dissociation of HCO^3- into CO₃^2-. It is necessary to simplify these reactions as a simple model, which is used to analyze the transport system. From experiments in the liquid membrane with alkaline buffer solution, it si shown that the flux of CO₂ into K₂CO₃/KHCO₃ aqueous solution can be enhanced by the presence of CO₃^2-. A diffusion model with an overall reaction based on the film theory is proposed that proposed that predicts the experimentally observed facilitation factor with resonable accuracy. The present model is compared with the rigorous diffusion model involving the complicated conventional chemical reactions.