Cathodic protection (CP) is a technique to control the corrosion of a metal surface by making that surface the cathode of an electrochemical cell.

It is a method used to protect metal structures from corrosion. Cathodic protection systems are most commonly used to protect steel, water/fuel pipelines and storage tanks; steel pier piles, ships, offshore oil platforms and onshore oil well casings.

A side effect of improperly performed cathodic protection may be production of molecular hydrogen, leading to its absorption in the protected metal and subsequent hydrogen embrittlement.

Cathodic protection is an effective method of preventing stress corrosion cracking.

  
Aluminium anodes mounted on a steel jacket structure