Corrosion inhibitors used to mitigate internal corrosion in upstream oil and gas industry pipelines are typically surfactant compounds that contain nitrogen sulfur phosphorus and/or oxygen in particular functional groups whose mechanism of inhibition is by formation of a protective film on the metal surface. Those films have been correlated to adsorption isotherms by assuming that the coverage of the metal surface is equal or proportional to the corrosion mitigation efficiency. Although adsorption isotherms are used to predict the corrosion rate as a function of corrosion inhibitor concentration they do not describe the corrosion mechanisms affected nor predict the change in corrosion potential. The goal of this research is to explain and analyze the reactions affected and the shift in corrosion potential due to the presence of corrosion inhibitors. Two inhibitors were tested and analyzed: (TOFA/DETA) imidazoline-based corrosion inhibitor and alkyl benzyl dimethyl ammonium chloride-based corrosion inhibitor. Experiments were conducted with a three electrode system in a 2 liter glass cell using an X65 steel rotating cylinder electrode as the working electrode. Linear polarization resistance and potentiodynamic polarization were taken to obtain corrosion rates and information about the anodic and cathodic reactions. In order to explain the behavior of such reactions a mechanistic model was developed by using electrochemical kinetics and two parameters to define inhibition: a mitigation factor ? which accounts for the overall reduction in the anodic and cathodic reactions and potential-dependent Tafel slopes which account for changes in reaction kinetics due to the addition of non-conductive species adsorbed on the metal surface. The electrochemical reactions affected by the quaternary ammonium chloride were modeled by using a mitigation factor with no change in Tafel slopes. On the other hand electrochemical reactions affected by the imidazoline-based corrosion inhibitor were modeled by using a mitigation factor and potential-dependent Tafel slopes.