An integration of water vane pump and hydraulic vane motor was introduced in small reverse osmosis (RO) system, in which the hydraulic vane motor was used as energy recovery device. The hydraulic performance and energy consumption of one combination of pump and hydraulic motor were investigated under different operation conditions. This type of integration pump reduces energy cost and simplifies the system setup, thus it could be an alternative choice for small RO desalination system. Our results demonstrated that the improvement of volumetric efficiencies of the pump and the hydraulic motor was the main factor to increase the prototype pump performance. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.