References and illustrations at end of paper.Marine growth and corrosion in sea water piping and heat exchangers, if uncontrolled, can result in increased operating and maintenance costs. Fouled piping and heat transfer surfaces cut down the cooling water flow, resulting in increased fuel consumption and, therefore, more frequent cleanouts.In addition, these fouling sites can lead to accelerated corrosion which, if unchecked, results in eventual expensive equipment renewal. Conventional marine groth control technology, most commonly chlorination, is coming under increasing environmental scrutiny and can itself lead to increased corrosion problems if not carefully controlled. This paper will present the results of research and field experience with an electrolytic system for controlling both marine growth and corrosion in sea water service systems.