Abstract: Volumetric liquid-phase mass transfer coefficients as well as gas-liquid interracial area for oxygen-water and oxygen-aqueous-C7F15 COONa-solution systems were determined in a horizontal stirred vessel by steady-state oxygen absorption and light scattering experiments. The horizontal agitated ves-sel is considered to possess more advantages than the vertical vessel, such as lower agitation speed tor normal gas-liquid mass transfer, greater kLa for the same agitation power, improved mixing, and homogeneity in mass transfer area distribution. The paper deals with differences of mass transfer characteristics between these two types of vesseis on the basis of hydromechanics, and gives correlations of the experimental results The objective of the paper is to provide basic data tor developing processes for manufacturing fluorine-containing polymer.