In order to improve the mixing performance in an agitated vessel, a very unique method to insert an object into a vessel agitated by an impeller was proposed and an experimental investigation of mixing performance was conducted. The objects inserted move so as to destroy the isolated mixing regions above and below the impeller, which are usually observed for vessels stirred by ordinary small impellers under steady mixing conditions. As a result, it was demonstrated that the method proposed in this work has a significant enhancement of mixing efficiency at low Reynolds numbers. This method may bring a new innovational agitator system. (C) 2009 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.