Two main commercial in-line high shear mixer (HSM) configurations, including the dual rows ultrafine teethed and the single-row blade-screen in-line units, were investigated under the pump-fed mode in order to disclose the pump capacity and power consumption characteristics. Results indicate that the pump capacity of the teethed in-line HSM is rather poor, with maximum pumping heads of 2.31-2.72 m and a maximum pumping efficiency of 1.5%. By contrast, the blade-screen in-line HSM demonstrates maximum heads around 4.33-4.76 m and a maximum pumping efficiency of 7.3%. The power number data of both units with the bearing loss subtracted can be correlated by the Froude number modified power consumption model. The predicted power numbers show good agreement with the experimental data for both in-line HSMs. The results obtained here are fundamental for the performance assessment as well as the design and selection of in-line HSMs.