The three key aspects of the top of the line corrosion process are condensation, chemical
speciation and corrosion. The focus of this study is on the condensate speciation through a
thermodynamic approach. Specifically, the aim of this study is to determine the concentration of acetic
acid in the condensate. The presence of acetic acid tends to increase the corrosion rate and to promote
localized corrosion. The results of this study show that the concentration of free acetic acid in the
condensate is determined predominantly by the pH of the liquid phase, which is changed by the
corrosion process. The concentration of total acetic acid seems to decrease as the condensation rate
increases. The understanding and results gained from this study will lead to the creation of a complete
predictive model for top of the line corrosion.