Nowadays it is an operational routine to clean the flue gases from glass furnaces to remove noxious air pollutant substances. The established processes are highly effective, however, there are failures caused by the condensation of aggressive fluxes inside the large and expensive flue gas filters. To this day, the process control of the flue gas purification equipment is based on empirical data and experience. Currently available data do not allow to base process design and control on a solid thermodynamic and kinetic foundation. It is the aim of this work to find out under which condition condensation really takes place. Therefore the first results of collected kinetic data on the condensation from the system Na2O-H2O-SO2-O2-Co2 are shown to estimate the dew points of liquid and solid condensates as a function of flue gas composition and temperature.