This paper presents a mathematical model to describe a three-fluid electroosmotic focusing/pumping techniques, in which an electrically non conducting fluid is focused and delivered by the combined interfacial viscous force of two conducting fluids and pressure gradient. The two conducting fluids are driven by electroosmosis and pressure gradient. The electrical potential in the two conducting fluids and the velocity distribution of the steady three-fluid electroosmotic stratified flow in a rectangular microchannel were presented by assuming a planar interface between the three immiscible fluids. The effects of viscosity ratio, electroosmosis and pressure gradient on velocity profile and flowrate are analyzed to show the potential feasibility of this technique. (C) 2009 Elsevier Ltd. All rights reserved.