The corrosion behavior of carbon steel in CO2-saturated artificial geothermal brine was tested in the absence and presence of an amine-based inhibitor by weight loss tests and electrochemical measurements. Experimental conditions were adapted to the conditions existing on the re-injection sites of geothermal power plants located in the Upper Rhine Graben. The influence of Ca2+-ions on the corrosion behavior due to scale formation and its impact on inhibitor performance was investigated. Inhibitor adsorption was strongly dependent on inhibitor concentration, Ca2+ concentration in the brine, reaction time, and pre-corrosion of the metal surface.