Reverse osmosis is nowadays the predominating process for the production of fresh water by desalination. Progresses in the prediction of reverse osmosis performance are highly valuable for the rapid and inexpensive optimization of the operating conditions. The interaction of the membrane properties and the dominant phenomena (concentration polarization, osmotic pressure...) turns into a complex scientific problem, tackled in this study by a numerical modelling-simulation-experimentation approach, a central topic for chemical engineering.