The paper is dedicated to development of the catalytic process for controlled SO3 production for conditioning of flue gases from coal-fired power plants. On the basis of comparative technological analysis performed for different variants of the process arrangement, it was shown that optimal technological decision is catalytic sulfur dioxide oxidation in synthetic SO2-containing stream in a separate reactor with two adiabatic beds of catalyst with following introduction of SO3-containing flow into the main coal boiler gas duct. Undoubted benefits of this process are: complete independence of the process from the flue gases properties; possibility to control SO3 concentration in the flue gases in the wide range; possibility to process gases with high SO2 concentration. providing low gas flow rate and low catalyst loading; absence of limitations for the pressure drop of the catalyst bed. Among catalysts on the basis of fiber-glass support the best catalytic performance was observed for platinum-containing catalyst on support modified with zirconium dioxide. It was demonstrated that optimal catalyst solution is combination of conventional granular vanadia and platinum woven fiber-glass catalysts, providing high activity both at high and low temperatures. (C) 2009 Elsevier B.V. All rights reserved.