The gas-liquid mass transfer of rotor-stator spinning disc reactors is studied for various operating conditions and different reactor geometries with rotor radii between 0.065 and 0.135 m. A new reactor setup with a perforated disc containing 119 narrow channels for direct dispersal of gas into the reactor cavity is examined. High volumetric mass transfer coefficients of up to 12 m(1)(3) m(R)(-3)s(-1) can be observed due to the large energy input at high rotational disc speeds of up to 2000 rpm. The combination of high turbulence and small gas bubbles as a result of the large shear forces in the cavity is identified to be responsible for the acceleration of the mass transfer at high rotational disc speeds. Correlation with an extended power law model equation allows the first-time quantification of the impact of the main operating parameters such as gas and liquid flow rate and rotational disc speed on the volumetric mass transfer coefficients for different reactor geometries. (c) 2016 Elsevier B.V. All rights reserved.