The aim of the study was to investigate the possibility of using water cooled thin wall structures in fire compartmentation of industrial buildings. How to prevent fire spread through doors, windows or other openings in the fire walls has also been included in this study. A litterature investigation about water cooling of fire exposed structures has been made. This shows that in offshore and oil terminals water sprays have been applied in cooling fire exposed structures. As fire compartmentation water, according to the litterature investigation, is not used in Sweden. Other countries have not reported to have such a kind of compartmentation method, either. Results from oil storage tank tests show that a water flow density of 10 l/min/m² is essential to completely wet the surface of the tank. If the same flow density was applied to large industrial walls of thin plate, the water demand and hence the costs of walls with pumps and pipings would be compareable to conventional walls of concrete. If economical winnings with this compartmentation method would be made, the water demand should be reduced. The water demand could be essentially reduced by covering the wall by a rough layer of some fire proof material. Hence, the water drainage could be smaller and water would have more time on the wall surface to vaporize. Thus the heat of vapourization could cool the wall more effectively. According to theory it is essential not to allow the metal surface to get hotter than about 300 °C. Above this temperature the water drops do not get stuck on the metal surface resulting a drastic increase of water demand.