Well-defined poly (meth)acrylates and polystyrene with predetermined molecular weights and low dispersity were prepared by electrochemically-mediated Atom Transfer Radical Polymerization (eATRP), catalyzed by Cu complexes with amine ligands in a stainless-steel reactor. eATRPs were triggered by feeding a small current through the reactor scaffold used as a cathode. Moderate to high conversions were achieved in a short time. Chain extension confirmed high chain-end fidelity. ICP-MS analysis showed that the stainless-steel reactor does not release ions in solution; if a current is not applied, it cannot trigger polymerization as in zerovalent metal mediated ATRP. Successful laboratory scale-up tests were performed in the same reactor with a higher reaction volume (40 mL instead of 10 mL). The proposed setup is flexible and cost-effective, and in principle could be used for eATRP of a large variety of monomers. (C) 2019 Elsevier Ltd. All rights reserved.