Carbon capture and storage (CCS) includes processing of supercritical carbon dioxide (scCO(2)). The carbon dioxide (CO2) stemming from flue gases contains acid forming impurities, especially in the case of coal fired power plants. In the present work, the mobility and reactivity of acids in supercritical scCO(2) was investigated. The corrosive attack of low alloyed carbon steel (material 1.0484) by water (H2O) alone in scCO(2) was negligible. Nitric acid (HNO3) was very mobile and corrosive towards the carbon steel while sulfuric acid did not migrate through the scCO(2) to react with the steel surface. Hydrochloric acid in scCO(2) was very mobile and reactive towards both carbon steel and high alloyed test equipment. Gravimetric analyses revealed a severe material loss after corrosion in the presence of HNO3. Thickness measurements showed localized material losses. (C) 2012 Elsevier B.V. All rights reserved.