The pitting corrosion of carbon steel in carbonate-formation water solution in the presence of chloride ions and the effect of addition WO42-, MoO42- and NO2- anions on the pitting corrosion were studied using cyclic voltammetry and potentiostatic current-time measurements and complemented by scan electron microscope (SEM), energy dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS) investigations. Cyclic voltammograms of carbon steel in the presence of chloride ions in carbonate-formation water solution show one anodic peak, corresponding to the formation green rust carbonate and the two cathodic peaks. As the addition of Cl- ions concentration increases, the anodic peak current density increases and pitting potential E-pit shifts to more negative potential. It is shown that the rate of pit initiation (t(i)(-1)) decreases and the pitting potential Epit moves to more positive direction upon the addition of inorganic anions. It was found that pitting inhibition of carbon steel increases in the sequence: (WO4)(2-) > (MoO4)(2-) > (NO2)(-) (c) 2007 Elsevier Ltd. All fights reserved.