The present study investigated the feasibility of RF electrical fields in mitigating CaCO3 fouling in cooling water. Three different voltages and two frequencies were used for the RF electric fields produced directly in water with varying cold-side velocity. Artificial hard water was used. Fouling resistances for the PWT-treated cases decreased by 34-88% from the values for no-treatment cases, depending on the cold-side flow velocity. The results showed blunt crystal structures for the PWT-treated cases, while no-treatment cases had sharp and pointed crystal structures. The new PWT method using RF electric fields presents a valid tool to mitigate CaCO3 fouling in cooling water. (C) 2009 Elsevier Ltd. All rights reserved.