The occurrence of localized corrosion in Top of the Line Corrosion (TLC) was investigated in sweet (CO2-dominated) environment with a focus on understanding the influence of the environmental parameters on localized TLC in order to develop a narrative of the mechanism.A unique setup was developed for the experimental work involving the use of carbon steel inserts exposed to three different levels of cooling at the same time. This concept was quite successful in simulating realistic localized features. A series of long term exposure (one- to three-month) experiments was conducted to investigate the controlling parameters. The occurrence of localized corrosion could be very clearly correlated to the condensation rate the gas temperature and the organic acid content. Important observations on the morphology of localized TLC features could be made providing useful insight on the mechanisms involved.Keywords: Top of the Line Corrosion Localized corrosion