A new type of mixer, OCTAGIT, which can mix liquid with viscosity of up to several Pa . s and generate an unsteady flow with small power consumption, has been developed by Nomura Micro Science Co. Ltd.. This mixer has a double disc type impeller which is operated by double shafts. OCTAGIT generated many vortex rings to provide good liquid mixing over a wide range of viscosity. To evaluate the performance of OCTAGIT, the mixing time, profile of circulating time and power consumption were measured. In the turbulent region, OCTAGIT has a circulating time profile with only one peak of frequency, and the mixing time is shorter than that of a disc turbine operating under the same power consumption per unit volume.