This document specifies the requirements for the external and internal cathodic protection for offshore wind farm structures. It is applicable for structures and appurtenances in contact with seawater or seabed environments. This document addresses: — design and implementation of cathodic protection systems for new steel structures; — assessment of residual life of existing cathodic protection systems; — design and implementation of retrofit cathodic protection systems for improvement of the protection level or for life extension of the protection; — inspection and performance monitoring of cathodic protection systems installed on existing structures, and — guidance on cathodic protection of reinforced concrete structures.