In the Membrane Technology Group (MTG) of KU Leuven, polymer-based membranes are developed for a variety of applications. Selected examples will be highlighted in this talk of membranes for gas separation, solvent-resistant nanofiltration, RO, membrane bioreactors and redox flow batteries. They are prepared via phase inversion or interfacial polymerisation. The production of some of them is currently being upscaled to allow continuous, roll-to-roll membrane preparation and pilot-scale testing.