Flue gases from 3 Polish sewage sludge incineration plants were neutralized with dry NaNCO3. The solid product was analyzed for Na2CO3, NaHCO3, NaCl, Na2SO3, Na2SO4 and NaF contents to det the stoichiometric coeft of the reaction. The flue gas purffin. systems were less efficient (except for Cracow plant) than the similar plants operated in the European Union.