Monoethylene glycol (MEG) is a gas hydrate inhibitor. The large amounts used in gas field industry impose the need for MEG regeneration. During this process the water-MEG mixture is heated at low pressure to remove most of the water. It is important to know the carbon dioxide equilibria under MEG regeneration conditions to prevent problems related to mineral precipitation and scale formation. The equilibrium amount of total CO(2) in solution was therefore examined in water-MEG solutions at typical MEG regeneration conditions [(50 to 98) %wt MEG, (80 to 140)degrees C, (SO or 100) mmol.kg(-1) total alkalinity]. A CO(2)/N(2) mixture of known composition (0.200 % or 0.050 % mol CO(2)) controlled the CO(2) pressure in the reaction vessel. Discoloration was observed in some experiments, and ion chromatography showed that glycolic and fon-nic acids were the dominating MEG degradation products. Data for the total CO(2) concentration at equilibrium are reported together with a discussion describing why common acid titration is still a valid analysis method although significant amounts of organic acids were present.