Two single‐stage, 6 GHz electron cyclotron resonance (ECR) ion sources are currently in use at the ARENAS project at Louvain‐la‐Neuve. One of them is used to ionize radioactive elements to low charge states (1+to 4+) before injection in the postaccelerator cyclotron. High intensity beams of6He,11C,13N,18Ne, and19Ne are being produced. Recently the source has been adapted for the ionization of18F and the first experiment with this beam has been performed. A second ECR source, almost identical to the first, is used in combination with the Leuven isotope separator on‐line. It produces stable and radioactive beams at 50*qkeV. Mass separated beams of13N,14O, and15O can be produced using a high‐temperature carbon target. An upgrade of this type of ECR source is now under construction. It consists mainly of increased magnetic fields and the capability for insertion of a heated cavity. ©1996 American Institute of Physics.