A process of reducing scaling of a metal surface exposed to an aqueous solution from which scale may form after a period of exposure. The process comprises applying a cathodic potential to the surface for at least some of the period of exposure. In some cases, e.g. when an article is made of a ferrous metal, it is advantageous to coat the article with a different metal (e.g. copper or an alloy of copper) before applying the cathodic potential to avoid hydrogen generation and excessive current flow. An article to be protected from scaling may also advantageously be electrically isolated from other parts of an apparatus.