A rotary energy recovery device (RERD) is widely used in a reverse osmosis desalination system. In order to maintain the device running in an available torque and obtaining a long service life, a portion of high pressure seawater is usually sacrificed to work as lubrication to reduce the friction torque of the device. However, when using such method, a certain amount of energy recovery efficiency will be lost due to the lubrication or leakage. This paper focuses on improving operating performance of a rotary energy recovery device by making textured grooves on the surfaces of two end covers of the REED. The experimental results show that compared to the untextured REED, the textured READ reduces the device's torque by half, and successfully improved the efficiency by 40% under the mating clearance of 0.035 mm, operating pressure of 6.0 MPa and rotary speed of 500 rpm. In addition, thanks to the groove textured surface which dramatically reduces the RERD's torque and permits the mating clearance to be minimized. Under the small clearance of 0.025 mm, the energy recovery efficiency of the textured REED can be increased up to 96.3% at an operating pressure of 6.0 MPa which can well satisfy the requirement of the industry application. (C) 2015 Elsevier B.V. All rights reserved.