Thermally insulated steel surfaces are very challenging with respect to corrosion protection for several reasons. High temperature and temperature cycling is generally demanding for protective organic coatings. Moisture frequently penetrates the insulation mantling and provides a very corrosive environment. The mantling also prevents the moisture to escape and the corrosive environment is trapped. Finally the insulation prevents efficient inspection of the state of the coating. Hence the corrosion can develop to a severe state without being discovered. Selecting suitable coating products are therefore important and methods for testing coating resistance to degradation under thermal insulation are sought.A test method was presented by Haliday in 2005 (Halliday Paper No. 0520 CORROSION/2005) which has been used in this work. Four different coatings have been tested: TSA an amine cured epoxy an epoxy novalac and a temperature resistant inorganic paint. In the method the sample has a temperature gradient so the coating is exposed to temperatures from ambient to 400 °C. In addition the temperature is cycled and a corrosive electrolyte is added.The paper discusses performance of the coatings as function of temperature exposure temperature gradient along the sample and coating properties.