The corrosion inhibition characteristics of acetylsalicylic acid on carbon steel has been studied using electrochemical measurements. Results showed that: The inhibition efficiency values give maximum inhibition at the concentration of 300 ppm and decrease back. They decreased with increasing temperature. Polarization studies showed that this compound is an anodic inhibitor for carbon steel in decanted water from a tank bottom hydrocarbon storage (East Region Transport: Skikda Algeria ). The inhibition occurs through adsorption of the inhibitor molecule on the metal surface. The adsorption of the inhibitor on the metal surface is found to obey Langmuir’s adsorption isotherm. The values of thermodynamic parameters, such as Kads, G°ads, H°ads and S°ads are calculated