A predictive model was developed in this study for simulating the development of membrane fouling with time in full-scale RO processes. The increase in resistance was used as an indicator of membrane fouling and it enabled one to better describe membrane fouling taking place in a long membrane channel. In this model, fouling potential of a feed water was defined as the increment in membrane resistance due to a unit volume of permeate passing through the membrane, which was directly measurable with a simple filtration experiment. By employing the concept of fouling potential, fouling property of a feed water could be directly related to fouling rate on a RO membrane. The local variations in flow properties and parameters were explicitly taken into consideration in the model in order to provide a more realistic description of a full-scale RO process. The results of the simulation studies demonstrated that a full-scale RO system could maintain a constant average permeate flux for a period of time even though fouling development had occurred right from the start of operation. The effects of water fouling potential, channel length, and membrane resistance on fouling development in full-scale RO processes were investigated. (C) 2004 Published by Elsevier B.V.