In a wiped film apparatus, the hydrodynamic conditions of the flow have a direct effect on the film thickness and on the residence time of the molecules and thus on the effectiveness of mass and heat transfer. Measurements of the residence time distribution (RTD), for different stirring velocities, allowed to propose a model for the flow as a series of perfectly mixed cells in parallel with a series of perfectly mixed cells exchanging mass with a dead zone. (c) 2005 Elsevier Ltd. All rights reserved.