Wet flue gas desulphurization (WFGD) in power plants causes significant decrease of flue gas temperature and increase of their humidity. It results in intensive condensation of flue gas in chimneys’ ducts. For this reason chimneys that carry out the flue gases fromWFGD are called wet chimneys. The aim of the article was to present the selected operating problems of these objects. The risk of corrosive degradation of wet chimneys was discussed. The examples of the influence of strongly aggressive flue gas condensate on the degradation of construction elements and flue gas ducts are presented. The attention was drawn to aspects, which have to be taken into consideration at the stages of designing and exploitation of wet chimneys. Keywords: wet chimneys; power plants.