C02 corrosion of carbon steel and its inhibition in mixtures of water and ethylene glycol (MEG) or diethylene glycol (DEG) has been studied at 1 bar CO2, 25°C, pH 5 under natural convection conditions. Corrosion rates predicted by the glycol correction factor of DeWaard et al. were in mutual
agreement with the experimental results. Analysis of the experimental results shows that the ccmosion inhibitor effect of MEG and DEG can be correlated to changes in solution properties with increasing MEG or DEG concentration, such as decreased CO2 solubility, decreased CO2 diffusivity / increased solution viscosity, decreased water activity and decreased solution polarity. Also described is an impurity related corrosion inhibition that can be very efficient, and possible ways to improve the inhibitor effect of glycol solutions by adding small amounts of inhibitor compounds. Keywords: carbon dioxide, corrosion, glycol, carbon steel, inhibition, viscosity, CO2 solubility