In many polymer manufacturing processes, mass transfer operations between a high viscosity liquid and gases are applied, but mass transfer rates have been explained only using k(L)a. We measured k(L) for molten polystyrene and corn syrups by using a rotating cylinder with surface renewal action in which surface area was known. As a result, it is proved that (1) k(L) between gases and high viscosity liquids are expressed by Hibgie＇s penetration theory, and (2) diffusivities are obtained from measurements of k(L) in corn syrup-CO2 and glycerine-CO2 systems.