In this study, corrosion rates of carbon steel in hydrogen sulphide (H2S) and carbon dioxide (CO2)�H2S condition are reported from Electrochemical Impedance Spectroscopy (EIS) measurements and potentiodynamic polarization. The electrochemical measurement method has been utilized in monitoring the behaviour of carbon steel in 0.01 M H2SO4 solution containing different concentrations of H2S. As the concentration of H2S increases, the corrosion rate of the carbon steel also increases. This is due to the fact that the hydrogen evaluation reaction has been encouraged as the H2S accelerated in proportional of H2S concentration. On the other hand, under CO2�H2S condition it shows a different trend compared to the H2S-only condition. As the concentration of H2S increases, the corrosion rate decreased. © Institute of Technology PETRONAS Sdn Bhd (Universiti Teknologi PETRONAS) 2024.