Mass transfer characteristics in a rotor-stator reactor in terms of the overall volumetric mass-transfer coefficient (K(x)a) using the N-2-H2O-O-2 system were investigated. The effects of various operating parameters including rotation speed, liquid volumetric flow rate, and gas volumetric flow rate on Kxa were systematically examined, and a gas-liquid mass transfer model was established to predict Kxa. Results reveal that Kxa increased with higher rotation speed, liquid volumetric flow rate, and gas volumetric flow rate. The results also confirm that the predicted values of K(x)a were in agreement with the experimental values with deviation within 15 %. The results contribute to a better understanding of mass transfer characteristics in rotor-stator reactors.